Domestic overheating risks and mitigation strategies: The state-of-the-art and directions for future research

Abstract

Anthropogenic climate change will likely put dwellings at risk of overheating and potentially increase cooling demand in the decades ahead, leading to higher greenhouse gas (GHG) emissions due to the energy consumed for mechanical cooling. Contemporary constructions with highly insulated fabric have been found to suffer from periodic overheating in today’s climate, the occurrence of which is projected to increase in frequency as the temperature rises. This critical review investigates the factors affecting overheating risks in dwellings and passive cooling strategies to mitigate overheating impacts on occupant thermal comfort and wellbeing. The cooling efficiency of passive strategies is affected by the design, construction and operation of buildings, as well as climate and occupancy. A framework has been developed to illustrate the effect of overheating factors on the cooling efficacy of passive strategies. Findings suggest that a combination of passive strategies is required to minimise overheating risks by the 2080s. External solar shading is the most effective method for retrofitting insulated dwellings. On the other hand, cool paint is ideal for uninsulated dwellings. In addition, thermal mass and natural ventilation require occupant interaction for optimal air circulation and cooling performance.

Keywords

Overheating thermal comfort passive cooling climate change dwellings

Introduction

The scarcity of fossil fuels, stringent greenhouse gas (GHG) emission targets and anthropogenic climate change are all factors that contribute to the demand for passively cooled buildings.¹ Buildings account for 36% of global energy consumption and 40% of carbon emissions.² The UK residential sector accounted for nearly 68 MtCO₂e of GHG emissions in 2020.³ Peak summer temperatures in the UK could increase by 10°C by the 2080s compared to the 1990s reference climate.⁴ Furthermore, the mean summer temperature will likely increase by 5.4°C and 2.8°C in southern England and northern Britain, respectively, by the 2080s.⁵ Indoor overheating has already been identified in British^4,6–9 and European dwellings¹⁰ and is likely to increase as a result of global warming,^11,12 which in turn will increase the cooling demand for maintaining occupant thermal comfort. Without significant abatement measures, the level of GHG emissions will continue to increase, leading to a much warmer climate. Therefore, it is vital to implement passive cooling strategies at the construction and retrofit stages to mitigate overheating risks without increasing the need for mechanical cooling in a warming climate.

Overheating refers to the occurrence of high internal temperatures which cause thermal discomfort, affecting occupants’ health and productivity.¹³ Overheating risks are projected to rise due to climate change,^14–16 where external peak temperatures similar to heatwave patterns will be greater and recurring.¹⁷ During the 2003 heatwave across Europe, around 70,000 deaths¹⁸ were reported, of which an approximate of 30,000 and 2091 were from Western Europe¹⁹ and England,²⁰ respectively. Consequently, public health stakeholders in the UK²¹ and Europe²² raised their concerns and called for preventative measures to reduce heat-related deaths. Heat-related deaths are more pronounced in urban regions due to the urban heat island effect,²³ for example, London experienced higher heat-related mortality due to its building density.²⁴

An overview of factors affecting overheating risks in dwellings, their impacts on occupants and potential solutions are presented in Figure 1 as a starting point for the contextual discussion. Dwelling characteristics and the design, together with climate and environmental features, affect overheating risks. The impacts on occupants range from sleep deprivation and reduced productivity to even death. Various solutions to overheating are found in the literature, ranging from passive solar shading to improved thermal properties of materials by adding more insulation. Assessment methods used for overheating are based on thermal comfort criteria.

Figure 1.

An overview of factors affecting overheating, its impacts on occupants and potential solutions to the problem.

This paper provides a critical overview of previous findings to enhance comprehension of the topic and recommend future research directions.

Methodology

This section outlines the steps to acquire the relevant literature for this review, as displayed in Figure 2. A systematic literature review (SLR)²⁵ was conducted with the following research questions: ‘What necessitates adaptation of the housing stock against overheating?’, ‘What are the influencing overheating factors?’, ‘How does overheating risk vary for different dwelling constructions?’ and ‘What are the most significant passive cooling strategies to reduce overheating risks?’. Using ‘overheating in dwellings’ as a broad search keyword, themes were found from the titles of the selected papers, and descriptors were derived from the identified themes. In the search engines of ScienceDirect, Taylor & Francis, Scopus and Google Scholar, Boolean operators were employed in conjunction with the descriptors; ‘AND’ was used to combine search terms, while ‘OR’ was used to account for synonyms, as shown in Table 1. The term ‘overheating’ has been combined with all passive strategies to cover studies investigating the influence of overheating on the passive strategies’ cooling efficacy. For instance, ‘overheating’ AND ‘cool paint’ OR ‘cool roof’ OR ‘cool wall’ OR ‘albedo’ was searched to obtain papers investigating the use of cool paints against overheating risks. Different phrases were combined for more specific searches. For example, to find papers related to natural ventilation to prevent overheating in Passivhaus constructions, ‘overheating’ AND ‘Passivhaus’ AND ‘natural ventilation’ were used as the search terms.

Figure 2.

The methodology used for the literature search.

Table 1.

Search strings used for finding the literature.

Search strings and Boolean operators
AND	OR	Theme
“overheating”, “natural ventilation”	“window opening”	Natural ventilation
“overheating”, “vegetation”	“green roof”, “green wall”	Vegetation
“overheating”, “solar shading”	“fixed shading”, “solar protection”, “shutter”	Solar shading
“overheating”, “thermal mass”	“PCM”, “heavyweight construction”, “lightweight construction”	Thermal mass
“overheating”, “cool paint”	“cool roof”, “cool wall”, “albedo”	Cool paint
“overheating”, “passive cooling”, “wall insulation”	-	Wall insulation
“overheating”, “Passivhaus”, “natural ventilation”, “thermal mass”, “cool paint”, “vegetation”, “wall insulation”	All the above strings for “OR”	Passive cooling strategies - Passivhaus

The papers received were mainly from peer-reviewed academic journals and conference papers. Papers in English text, where full text would be available, were considered. The relevance of the papers was verified in two stages: screening the abstract and reading the entire article. If a publication passed the first screening stage, the entire article would be read for further analysis. The most relevant studies were then subjected to the snowballing method; all citations in the relevant papers were inspected for consideration.

Analysis of the reviewed studies

The distribution of journals and conferences is shown in Figure 3. Most of the articles selected were in building energy-oriented journals such as Energy and Buildings and Building and Environment, which accounted for 16% and 13.4% of the total studies, respectively. Figure 4 shows the methodologies, overheating criteria and contexts of the studies reviewed, as well as the percentage of dwelling types. Only 8% of the studies adopted a mixed methodology of modelling and monitoring, with modelling methodology accounting for 58% of the total studies. More than half of the studies were conducted in the UK (60%). 27% and 13% of the papers were from Europe and other countries such as the USA, Australia and Canada, respectively. The Passive House Planning Package (PHPP) overheating criteria,²⁶ which was the least used overheating criteria, was used in 10% of the studies, followed by the Chartered Institution of Building Services Engineers (CIBSE) Technical Memorandum 59 (TM59).²⁷ Chartered Institution of Building Services Engineers Guide A²⁸ was used in 33% of the total studies, which was the most employed overheating criteria. Detached dwellings were the most considered dwelling type, considered in 28% of the studies, followed by purpose-built flats (21%), while converted flats were the least studied dwelling type. Both mid and end-terrace dwellings were considered for calculating the dwelling type percentage for studies on ‘terraced’ dwellings.

Figure 3.

Distribution of sources covered in this review paper.

Figure 4.

Distribution of dwelling types, thermal comfort criteria, methodology and the context covered in the reviewed publications.

Passive cooling need and occupant preference

Solid-walled constructions account for 31% of the 27.7 million dwellings in Great Britain,²⁹ of which are the least sensitive to overheating due to their low insulation levels.^6,7 Contemporary British building regulations emphasise on improving insulation to retain winter heat inside dwellings, which will likely increase overheating risks.^30–34 The UK housing stock is the oldest in Europe³⁵ and accounts for 25% of total national carbon emissions.³⁶ By the 2050s, over 80% of current housing stock will exist,³⁷ possibly requiring passive cooling strategies due to regulations supporting highly insulated constructions.

Occupants must adopt passive cooling strategies to decrease the use of mechanical cooling and to abide by the UK’s carbon emission targets for 2050.³⁸ Avoiding mitigation strategies may result in a drive to acquire mechanical cooling systems, as happened during the 2003 heatwave.³⁹ According to Peacock, Jenkins and Kane,⁴⁰ people in the UK may not be as willing to use air-conditioning units as in the US, but factors such as cheap operation and capital costs may encourage them. According to the authors, if UK occupants mimic US occupants’ behaviours, 550,000 London residences would have air-conditioning units installed by 2030. This estimate is likely to increase beyond 2030 because of a warming climate.

Meinke et al.⁴¹ investigated occupants' cooling preferences; fewer participants kept air-conditioning as their first choice once informed about the associated energy use. This finding implies that some individuals may not be aware of the causes of climate change or, more precisely, how their use of mechanical cooling may contribute to global warming. Nonetheless, this finding should be considered carefully because of the small number of occupants ( $n = 5$ ) who chose to save energy. Moreover, occupant perception of different passive cooling technologies was not considered. A more profound knowledge of adaptive behaviour and passive cooling efficiency, as suggested by Murtagh, Gatersleben and Fife-Schaw,⁴² can help society in mitigating the effects of climate change.

Overheating influencing factors

Occupancy

In addition to the number of occupants, occupancy factors that increase the risk of overheating include occupants’ vulnerability, building use and thermal comfort perception. The elderly are most vulnerable to overheating⁴³ because of their lack of mobility, which could limit the use of passive cooling measures such as natural ventilation.⁴⁴ Occupant behaviour influences overheating risks by altering the use of the adopted passive cooling measures and consequently their effectiveness.^16,45–47 Morgan, Foster and Poston et al.⁴⁸ found that occupants who used programmed ventilation did not report overheating within 26 dwellings, whereas 46% of occupants did not understand or use programmatic controls, resulting in varying overheating levels amongst dwellings. Ridley, Bere and Clarke et al.⁴⁹ discovered that occupants’ lack of operational knowledge of their louvres and exterior blinds contributed to increased solar heat gains during the summer. Baborska-Narożny, Stevenson and Grudzińska⁵⁰ found a 70% variation in overheating levels across 18 monitored flats adopting different ventilation practices; the household with the lowest risk of overheating efficiently used mechanical ventilation. These findings inferred that occupants lack awareness of how systems and passive cooling measures could significantly contribute to increased overheating levels indoors. Petrou, Mavrogianni and Symonds et al.⁴⁶ showed that when the number of occupants was increased, the internal mean temperature was increased in the bedrooms but not in the living rooms. Possibly owing to the limited sample size, the findings for five and six occupants were not statistically significant.

Internal heat gains

Previous research has demonstrated that internal heat gains influence overheating levels,^38,51–53 with impacts being more pronounced in living rooms.^7,47 This may be more common in flats where an open floor plan is more likely to be used, especially for the kitchen, dining and living areas. Peacock, Jenkins and Kane⁴⁰ established three distinct energy usage scenarios for appliances and cooking to analyse the effect of internal heat gains on overheating risk: scenario A (5682 kWh), scenario B (5064 kWh) and scenario C (5906 kWh). The research demonstrated that scenario C had more occupied overheating hours than scenarios A and B by 0.5% and 2.5%, respectively. The study highlights the effect of internal heat gains on internal temperatures, despite modest differences in electricity consumption, as a scenario with more tenants and greater electricity consumption may reveal a greater difference.

In a study by Lomas, Kane and Firth,⁷ occupants were given thermal sensors to install on their own, and only 48% of the monitored spaces had valid data. The authors claimed that the occupants’ misplacement of the thermal sensors, possibly near internal heat gain sources such as the appliances, resulted in an overestimation of internal temperature. The study showed the impact of internal heat gains on monitoring data for overheating analysis.

Dwelling construction

Different construction types may necessitate distinct passive cooling solutions to mitigate overheating risks.⁵⁴ Traditional constructions, such as solid-walled dwellings, are generally less susceptible to overheating due to their lack of insulation; nonetheless, the absence of solar shading^{15,45,46,50,55,56} and the presence of excessive glazing area^38,57 could increase the risk of overheating. On the other hand, energy-efficient constructions are well-insulated, which could require additional cooling energy to prevent overheating. Willand, Ridley and Pears⁵⁸ estimated that an additional 15.84 kWh/day of cooling energy was required to keep the living room in a 6-star dwelling at a 3-star dwelling’s temperature; the ascending order of star ratings designates the efficiency of Australian dwellings, where a 10-star rating is the most efficient. According to Sajjadian, Lewis and Sharples,⁵⁹ the cooling load in a Passivhaus detached dwelling in London in the 2080s would be 14 times that in 2011.

Table 2 summarises the key findings from the Passivhaus studies included in this review. Several studies have identified south glazing as an overheating factor in Passivhaus dwellings,^32,62,68 where either solar shading^32,68 or glazing ratio modification³² will be needed to minimise overheating risks. In addition, the Passivhaus overheating criteria could be modified to assess thermal comfort and account for occupants; occupants did not report thermal discomfort in overheated dwellings.^62,68 Post-occupancy resident training on building systems and efficient ventilation strategies⁴⁴ are also recommended to reduce overheating risks in Passivhaus dwellings.

Table 2.

Findings on overheating in Passivhaus dwellings.

Reference	Dwelling type (sample size)	Location	Methodology	Main findings
Hidalgo, Millián and Psomas et al.⁶⁰	Detached (1)	Spain	Monitoring	The dwelling passed the TM52⁶¹ overheating criteria but not the Passivhaus criteria²⁶ (11.4% over 25°C).
McLeod, Hopfe and Kwan³²	End-terrace (1)	UK	Modelling	Solar shading and the modification of glazing ratios effectively reduced overheating risks in the rooms with south-facing windows.
Ridley, Bere and Clarke et al.⁶²	Detached (1)	UK	Monitoring	The dwelling overheated in the summer, but the occupants reported no thermal discomfort.
Ridley, Bere and Clarke et al.⁶²	Detached (1)	UK	Modelling
Sameni, Gaterell and Montazami et al.⁶³	Flat (25)	UK	Monitoring	Regression analysis indicated that occupancy is the most influential factor in reducing overheating risks.
Fletcher, Johnston and Glew et al.⁴⁴	End-terrace (1)	UK	Monitoring	Overheating occurred during the cold months and nighttime.
Mlakar and Štrancar⁶⁴	Detached (1)	Slovenia	Modelling	Solar shading and natural ventilation provided thermal comfort in a hot and humid climate.
Ridley, Bere and Clarke et al.⁴⁹	Detached (2)	UK	Monitoring	Each dwelling’s susceptibility to overheating risk was influenced by its south oriented windows.
Colclough, Kinnane and Hewitt et al.⁶⁵	Semi-detached (3)	UK	Monitoring	Post-occupancy engagement is determined to be the key to understanding the thermal behaviour of highly insulated dwellings and improving occupant behaviour.
Mitchell and Natarjan⁵³	Flats and houses* (82)	UK	Monitoring	Fewer bedrooms passed the Passivhaus overheating criteria²⁶ when applied at room level and not building level.
Figueiredo, Kämpf and Vicente⁶⁶	Detached (1)	Portugal	Monitoring	Passivhaus construction is found to be feasible in the southern European climate, but different parts of the region could need different passive solutions to overcome overheating.
Figueiredo, Kämpf and Vicente⁶⁶	Detached (1)	Portugal	Modelling
Sage-Lauck and Sailor⁶⁷	Semi-detached (2)	USA	Monitoring	Phase change material (PCM) in semi-detached flats reduced overheating hours from 400 to 200 h.
Dan, Tanasa and Stoian et al.⁶⁸	End-terrace (4)	Romania	Monitoring	The occupants were unconcerned despite their dwelling failing the overheating criteria.
Dan, Tanasa and Stoian et al.⁶⁸	End-terrace (4)	Romania	Modelling

Note: * House types were not specified.

Dwelling design

Orientation

Dwelling orientation considerably impacts overheating levels due to the varying solar heat gains associated with different orientations. Gupta and Gregg¹⁵ found that west-facing flats had more overheating hours than south-facing flats by 22%. Espinosa, Symonds and Petrou⁶⁹ found that reduced glazing on the southwest orientation reduces overheating risks significantly, meaning that the south and west windows of flats are extremely sensitive to overheating. Habitzreuter, Smith and Keeling⁷⁰ showed that south-southwest oriented rooms were prone to overheating due to a lack of shading from nearby buildings. In addition, Dengel and Swainson³¹ discovered that southwest orientation posed a bigger risk of overheating in flats. Overall, the findings indicate that certain orientations make spaces more susceptible to overheating.

Layout

An open-plan kitchen and living room minimises overheating risk in flats, according to Espinosa, Symonds and Petrou,⁶⁹ and Gupta, Gregg and Bruce-Konuah.⁷¹ Espinosa, Symonds and Petrou⁶⁹ only looked at two-bedroom flats with varying floor plans, whereas Gupta, Gregg and Bruce-Konuah⁷¹ considered five dwellings without presenting their floorplans. The use of an alternative overheating criteria, such as TM52,⁶¹ may have been preferable in Espinosa, Symonds and Petrou’s⁶⁹ study due to TM59’s²⁷ difficulty to satisfy.⁷² Ji, Fitton and Swan et al.⁷³ discovered that bedrooms would overheat in the 2050s and 2080s, with less overheating reported in north-facing bedrooms with a fireplace below it. The finding indicates that warm air from the fireplace rose into the bedroom and accumulated, demonstrating the influence of floor plans on overheating levels.

Dwelling type

Flats are the most sensitive dwelling type to overheating risks,^{6,7,11,50,74,75} where the top floors are most vulnerable.^{38,57,70,76–78} Petrou, Mavrogianni and Symonds et al.⁴⁶ showed that converted flats had the lowest internal temperature compared to other dwelling types. On the other hand, Taylor, Symonds and Mavrogianni et al.⁷⁹ found that converted flats had the highest internal temperature. Unlike other dwelling types, converted flats have had little research on their internal conditions; thus, more research may be required to confirm their internal conditions. Many studies in the UK have shown that detached dwellings are least likely to overheat.^6,7,74,80 In a Dutch context, however, Hamdy, Carlucci and Hensen et al.¹¹ found it to be at the highest risk of overheating, along with flats. The difference in conclusions could be due to the architectural arrangement of the dwellings investigated in Hamdy, Carlucci and Hensen et al.’s¹¹ study, where the detached dwelling had considerable glazing area. The semi-detached dwelling in Hamdy, Carlucci and Hensen et al.’s¹¹ study, reported to be the coolest, did not have as many windows on the sides as the detached dwelling.

Bedrooms and living rooms

The CIBSE has developed static²⁸ and adaptive⁶¹ overheating criteria for bedrooms and living rooms. A lower static threshold criterion makes bedrooms more vulnerable to overheating than living rooms.^6,7,54,81 Lomas, Kane and Firth⁷ found a statistically significant relationship between the dwelling age and the temperature difference between the bedrooms and living rooms. In the energy follow-up survey,⁸² 30% of the living rooms in flats were overheated, compared to 12% in houses. In addition, living room temperatures were found to decrease with increasing floor area. Beizaee, Lomas and Firth⁶ discovered that living room temperatures were higher than bedroom temperatures in flats and significantly higher than the internal temperature of living rooms in other dwelling types. They also determined dwelling age as an influencing factor on the temperature differences between living rooms and bedrooms. Mitchell and Natarjan⁵³ found that 60% of the house bedrooms met the Passivhaus overheating criteria,²⁶ while 83% of bedrooms in flats did. Petrou, Mavrogianni and Symonds et al.⁴⁶ showed that bedrooms were cooler than living rooms in bungalows, converted flats and purpose-built flats. Wright, Young and Natarjan³⁹ found that during the 2003 heatwave, bedrooms were often marginally cooler than living rooms in London due to the greater prevalence of flats in London compared to Manchester.

Passive cooling strategies

Passive cooling has been recognised as a sustainable method for reducing cooling demand through heat transfer through conduction, convection and radiation.⁸³ There are three major types of passive cooling strategies: solar and heat protection, heat modulation and heat dissipation. Most passive cooling research is based on the Mediterranean climate, and recent warming trends suggest that the UK climate will resemble that of the Mediterranean in the future.⁴ Therefore, findings from studies of the Mediterranean climate could be a useful predictor of what may occur in the UK in the future.

Heat and solar protection

Solar and heat protection reduces solar heat gains indoors which lowers overheating risks. It is possible to install protections that prevent solar heat gains from entering the building to prevent the temperature inside from rising.

Vegetation

Plants on building surfaces provide cooling via evapotranspiration, while their soil layers provide insulation. Dry green roofs have high thermal resistance, which is beneficial for lowering winter heat losses.⁸⁴ Zinzi and Agnoli⁸⁴ investigated green roof cooling in Barcelona, Palermo and Cairo. Barcelona, which receives far more rainfall than Cairo or Palermo during the summer, had the greatest reduction in discomfort hours above 26°C. Gagliano, Detommaso and Nocera et al.⁸⁵ found that green roofs reduced cooling loads by 80% in Sicily, Italy, for the summer months (June to September). It could be that a green roof may cool a bungalow faster than a two-storey dwelling.

According to Virk, Jansz and Mavrogianni et al.,⁸⁶ insulated roofs decrease green roofs’ cooling effectiveness. However, the research was conducted on a four-storey office building in London, not a dwelling. This finding would likely indicate green roofs’ cooling potential if the same investigation was conducted in the domestic sector. Castleton, Stovin and Davison et al.⁸⁷ concluded that the cooling potential of green roofs could be optimised for the UK context by applying it to poorly insulated dwellings. Vegetation can be useful at the neighbourhood level by producing a cooling effect for the microclimate. Previous studies have shown that a decrease in the ambient temperature can be achieved if vegetation is applied at the neighbourhood level.^88–90 New constructions can be subjected to a vegetation requirement, which will result in a sufficient number of dwellings with vegetation per neighbourhood, providing a cooling effect at the neighbourhood level as well as cooling non-vegetated dwellings.

Wall insulation

Increasing the insulation level may increase the risk of overheating,^44,58,91 which could necessitate additional passive cooling measures. Tink, Porritt and Allinson et al.²⁹ found that internal wall insulation increases the risk of overheating in a semi-detached dwelling in Leicestershire. The authors claim the increased risk of overheating was low for that particular dwelling, location and time. This suggests that if future climate data had been used instead of 2015 temperature data, and a mid-terrace dwelling instead of a semi-detached dwelling was investigated in a different local setting, overheating hours may have been greater. Similarly, Porrit, Cropper and Shao et al.¹⁶ showed that the increase in overheating risk owing to internally inserted wall insulation was minimal, with the west-facing living room and east-facing bedroom having increased overheating hours. The family occupancy did not experience the increased overheating hours considering the different rooms and orientations. Mavrogianni, Taylor and Oikonomou⁹² found that a dwelling with internally placed wall insulation had a slightly higher internal temperature than a dwelling with externally placed insulation. It can be deduced that internally placed wall insulation tends to slightly increase overheating risk compared to externally placed wall insulation.

Solar shading

External and internal solar shadings have different cooling potentials, with external shading being the better option in most contexts. Tillson, Oreszczyn and Palmer⁹³ showed that external shadings outperformed dark and light internal shadings in preventing overheating; light-coloured roller and venetian blinds reduced the proportion of overheated housing stock by 27% and 18%, respectively. Porrit, Cropper and Shao et al.¹⁶ found that external shutters reduced degree hours over 26°C by 39% compared to internal blinds and curtains, which lowered degree hours by 20% and 15%, respectively.

Although several studies have identified solar shading as an effective passive cooling strategy for reducing overheating,^{13,15,16,33,75,94–97} its application in the UK may be limited due to the prevalence of outward window openings that external shadings could block.⁹⁸ In addition, solar shading reduces daylighting, which may affect occupants’ productivity and wellbeing. Habitzreuter, Smith and Keeling⁷⁰ found that external shading reduced overheating and daylighting by 74% and 30%, respectively. The effect of decreased daylighting reduces with increasing storeys, as the daylight factor increases. The average daylighting level was nearly the same for a low-rise flat without shading and a high-rise flat with shading. Baborska-Narożny, Stevenson and Grudzińska⁵⁰ found that occupants preferred sufficient daylighting over solar heat gains when choosing solar shading. The findings highlight the importance of balancing cooling reduction and daylighting in solar shading design.

Heat modulation

Heat modulation reduces internal temperatures and minimises substantial temperature fluctuations by utilising a building’s thermal mass. It differs from heat and sun protection in that it works when internal and external heat gains are present. In a warm climate, heat modulation may not be able to release stored heat and absorb additional heat, causing heat build-up.

Thermal mass

Thermal mass is the property of an indoor material to absorb and store heat over time; this lets the heat escape later and lowers cooling needs at peak times.⁵⁷ The thermal mass of heavyweight constructions is significantly greater than that of lightweight constructions. As a result of the summertime overheating of lightweight constructions,^78,96 regulators should focus on increasing their thermal mass. McLeod, Hopfe and Kwan³² discovered that the reduction of internal temperatures utilising thermal mass for the 50th percentile of climate data for the 2080s was more substantial than when using the 90th percentile data. Jimenez-Bescos⁹⁹ showed that thermal mass and night ventilation significantly reduced overheating using future climate data but not as much as using the 1970s climate data.

Phase change material

Phase change materials (PCMs) are a subcategory of thermal mass that can cool buildings passively. Their cooling performance comes from their capacity to absorb and release heat based on their phase change point, which is determined by their latent heat of fusion. The material transitions from the solid to liquid phase when heat is absorbed. When the indoor temperature decreases at night, the heat absorbed during the day is released until the PCM reaches its melting point and reverts to its solid phase. Phase change material can be incorporated into numerous building components, offering diverse potential for arrangement and composition, which can be useful for different contexts. Phase change material-enhanced wallboards are favourable due to their practicality in being incorporated into the building fabric, lower cost and overall cooling performance.¹⁰⁰

Auzeby, Wei and Underwood et al.¹⁰¹ tested PCMs in mid-terrace dwellings in Aberdeen, Newcastle and Southampton using climate data from the 2030s, 2050s and 2080s. The adoption of PCMs reduced domestic overheating in the investigated cities; however, the well-insulated construction was in a greater need of PCMs than the poorly insulated construction. Sajjadian, Lewis and Sharples⁵⁹ used the 2020s, 2050s and 2080s climate data to assess PCM’s cooling performance in a detached Passivhaus dwelling. Auzeby, Wei and Underwood et al.¹⁰¹ and Sajjadian, Lewis and Sharples⁵⁹ found that the PCM’s cooling efficiency is location and climate dependent, with the southern UK having the slightest decrease in overheating hours. They show that while PCM usage in dwellings may be beneficial until the 2050s, it cannot completely decrease overheating risks in the 2080s. As a result, when the external temperature rises, PCMs require additional passive cooling to maintain their cooling efficacy. However, Auzeby, Wei and Underwood et al.¹⁰¹ only looked at July, ignoring the heating season and the rest of the summer months, which may skew any conclusions based on a single summer month. Moreover, Sajjadian, Lewis and Sharples’⁵⁹ study was conducted in a Passivhaus dwelling, which has a different thermal environment than traditional dwellings.

The use of PCM has been investigated in other geographic regions. Fernandes and Costa¹⁰² modelled a standard family dwelling in Portugal to examine the cooling efficacy of PCMs and showed that PCMs are least effective for southern Portugal. PCM performance varies across Mediterranean and American cities, according to Ascione, Bianco and De Masi et al.¹⁰³ and Baniassadi, Sailor and Bryan,¹⁰⁴ respectively, with lower performance in hotter cities. It may be inferred that different UK regions may require different PCM compositions and arrangements for optimal cooling performance.

Heat dissipation

The process of releasing excess heat from a building through heat sinks at lower temperatures is referred to as heat dissipation. The method of heat dissipation works in a manner similar to that of heat modulation in that it is effective when heat gains are present within the building for them to be dissipated via convective heat movement, that is, natural ventilation removing excess hot air.

Natural ventilation

The movement of air provided by natural ventilation enhances the transfer of heat between the interior and exterior of a building. Depending on the external temperature, it is often used in the evening to draw in fresh air from outside and push out warm air from within the dwelling. Air changes per hour (ACH) is a common way to indicate the air exchange rate between an enclosed internal space and its external environment. The amount of cooling achieved by natural ventilation is subject to variables such as the size of the windows and the ventilation strategy used.

Different strategies must be adopted to optimise the use of natural ventilation for different constructions and climates. Shikder, Mourshed and Price¹⁰⁵ investigated the effectiveness of natural ventilation in Birmingham, Edinburgh, London and Manchester. The authors discovered that London would require the most ACH to prevent overheating. This means more adaptation measures are needed in the south UK before the 2050s to maintain or improve thermal comfort. Weng,¹⁰⁶ in a follow-up study to Shikder, Mourshed and Price,¹⁰⁵ concluded that nighttime ventilation would be more effective than daytime ventilation in the 2080s. However, depending on the location, using natural ventilation may compromise security. Roetzel, Dietrich and Busching et al.¹⁰⁷ claimed that the potential of window opening to dissipate heat gains could vary depending on its opening type and size. Different results may perhaps be observed for different opening types, with varying effectiveness of nighttime ventilation.

Peacock, Jenkins and Kane⁴⁰ adopted a window opening strategy in Edinburgh and London using the 2030s climate. Bedroom windows were left open throughout the night, ignoring noise pollution and security. Other windows in the dwelling were open if occupants were at home and closed at night; all windows were closed if occupants were not present. Edinburgh had nearly no degree hours above 28°C, while London was still at risk with 9.5%–11.5% of overheating hours considering different insulation levels and climates, reduced from 12% to 19%. This might imply that when the climate warms, the difference between the internal and external temperatures will be low, resulting in fewer heat exchanges. Improving the microclimate condition could be a solution to overcome such ineffectiveness. The study also revealed that natural ventilation is more effective for non-insulated dwellings.

Cool paint

Cool walls and roofs reflect significant amounts of solar heat gain owing to their albedo value, which decreases the temperature of the microclimate and surrounding interior thermal zone. As a result of its effective cooling in residential and urban settings,^{89,90,108,109} cool roof solutions are becoming increasingly popular.¹¹⁰ Pisello and Cotana¹¹¹ studied the performance of a cool roof on a residential building in Italy. In the summer and winter, the average operative temperature of the zone below the roof decreased daily by 2°C and 0.5°C, respectively. In July and January, peak temperatures were lowered by 4.7°C and 1.3°C, respectively. This study implies that cool roofs reduce summer cooling while causing modest winter heat losses. As the climate warms, extra passive cooling measures may be required alongside cool paint to reduce winter heat losses. The winter penalty can be minor in temperate zones, according to Gentle, Aguilar and Smith¹¹² and Barozzi and Pollastro.¹¹³ Nonetheless, the winter penalty produced by cool materials is not well documented in the UK. A monitoring study by Zinzi and Fasano¹¹⁴ assessed the cooling potential of an innovative white paint with high solar reflectivity made from a milk and vinegar mixture. The adjacent thermal zone’s temperature dropped significantly, proving that cool paints engineered to minimise cooling needs perform better than typical white paints on the market.

Combination of passive measures

Nighttime ventilation with daytime shading protects a solid-walled dwelling from overheating but may not prevent the increase in the internal temperature of dwellings with internal wall insulation.^94,115 Using solar shading and natural ventilation for a detached house in Germany, Banihashemi, Brasche and Lang¹¹⁶ obtained a significant cooling reduction. The combined use of solar shading and natural ventilation has also been of vital importance in preventing indoor temperatures from rising to critical levels in other European countries.^64,68,117

Findings on the combined usage of different passive cooling strategies are presented in Table 3. All studies adopted thermal simulation as their methodology, which could be due to time and cost constraints. Construction thermal properties, system design and operation, occupancy and weather are all factors that can affect modelling results. Referring to Adekunle and Nikolopoulou,¹¹⁸ monitoring and modelling studies indicated that 67% and 22% of spaces were overheated, respectively. This suggests that modelling could underestimate indoor overheating levels and should be treated more carefully.

Table 3.

Findings on the use of multiple passive cooling strategies.

Reference	Passive cooling strategies	Dwelling type	Orientation	Occupancy	Main findings
Capon and Hacker⁷⁶	- Solar shading - Cool wall - Cool roof - Insulation - Nighttime ventilation	Flat	- Southwest (living room and kitchen) (southwest) - Northeast (bedroom)	Two adults	- In the 2050s, the exceedance of occupied hours according to CIBSE Guide A²⁸ overheating criteria, for living rooms and bedrooms reduced from 67% and 41% to 26% and 8%, respectively. - Annual overheating hours for the semi-detached dwelling were reduced from 83% and 53% to 2.2% and 1.1% in the living room and bedroom, respectively.
Capon and Hacker⁷⁶		Semi-detached	Southwest	Two adults, three children
Ibrahim and Pelsmakers¹¹⁹	Combination 1:- Nighttime ventilation- Internal shading- External shadingCombination 2:- Nighttime ventilation- Improved glazing- External shading	Detached	North	Family	Exceedance of Passivhaus overheating criteria²⁶ reduced from 15% (2050s) and 22% (2080s) to 1% and 2%, 0% and 2%, respectively, for combinations 1 and 2.
Porrit, Cropper and Shao et al.¹⁶	- Cool roof- Cool wall- Nighttime ventilation- Window rules*- Curtains	End-terrace	West	Elderly	Overheating hours above the temperature threshold limit were reduced from 169 to 10 h for the living room and bedroom combined. The addition of fixed shading further decreased it to 3 h.
Porrit, Cropper and Shao et al.¹⁶	- Internal wall insulation- Light roof- Loft insulation- Nighttime ventilation- Window rules- Shutters	Mid-terrace	North	Family	Complete reduction of overheating hours was achieved.
Gupta and Gregg¹⁵**	Combination 1:- External wall insulation- Increased roof insulation- Low-e double glazing- Cool wall- Cool roof- Exposed thermal mass- Louvred shading	Mid-terrace	West	2 adults, 2 children	Combination 1 achieved the most reduction in overheating hours for the 2030s and the 2050s climates.For the 2080s, no combination of passive strategies sufficiently reduced overheating hours.
	Combination 2:- External wall insulation- Low-e double glazing- Cool wall- Cool roof- Thermal mass- Louvred shading	Semi-detached		2 adults
	Combination 3:- Increased roof insulation- Cool roof- Louvred shading	Detached		2 adults, 2 teens
	Combination 4:- External wall insulation- Increased roof insulation- Low-e double glazing- Cool wall- Cool roof- Louvred shading	Flat		Family
Orme and Palmer⁵⁷	- Thermal mass- Nighttime ventilation- Curtains- Reduced internal heat gains	Semi-detached	South	2 adults one child	The degree hours above 27°C was reduced from 100% to 20.3%–32.1% for different bedrooms.
Gupta and Du¹²⁰	Combination 1:- Window rules*- External shutter	End-terrace	South	Not specified	An average percentage of exceeding hours above 26°C and 28°C for bedrooms and living rooms was decreased from 25.7% to 1.1%, 0.5% and 0% (50^th percentile 2080s climate data) using combinations 1, 2 and 3, respectively.
	Combination 2:- Cool roof- Cool wall- Window rules*- External shutter
	Combination 3:- Cool roof- Cool wall- Thermal mass- Window rules*- External shutter

Notes: * Window rules prevent the use of window opening when the outside temperature is warmer than inside which in turn increases overheating occurrence as heat flows indoors. ** Each package is applied to all cases of different dwelling types and occupancies.

Ibrahim and Pelsmakers¹¹⁹ investigated two different combinations of passive cooling strategies; it is assumed that one is more occupant-dependent than the other owing to the existence of internal shadings. Both passive combinations significantly reduced overheating hours, indicating that adopting multiple passive cooling strategies may lessen the influence of occupancy on overheating risks. Furthermore, the effect of orientation on overheating risks may also be reduced. The reduction of overheating hours was almost identical for an elderly couple living in a west oriented dwelling to a family couple living in a north oriented dwelling.¹⁶

Combining multiple passive cooling strategies reduces overheating hours more effectively than employing a single passive strategy; however, its efficacy reduces as the climate warms. Based on the strategies suggested from the findings, it is evident that building envelope modification and limitation of heat gains are most effective in reducing overheating hours. Moreover, all the studies were conducted on traditional dwellings and not energy-efficient dwellings.

Efficacy of passive cooling strategies

This section analyses the cooling effectiveness of passive strategies based on the influence of different overheating factors. The occupancy factor is thought to be dependent on internal heat gains, which is why it was not picked for the framework. Three scales, ‘high’, ‘medium’ and ‘low’ were used to express the cooling performance of passive strategies. For example, ‘high’ in ‘weather’ implies that the passive cooling measure’s cooling efficiency is highly influenced by the corresponding overheating factor, that is, its cooling efficiency decreases as the climate warms, and ‘low’ in ‘dwelling type’ suggests that the changes in cooling efficacy of the passive measures are slightly influenced by different built forms. While ‘medium’, represents modest influences of the overheating factors on the passive strategies.

The optimum passive interventions for a warming climate are solar shading and cool paint, according to Table 4. Furthermore, solar shading offers significant cooling performance in both traditional and energy-efficient dwellings. Cool paint appears to be the least affected by different dwelling types and changes in orientation. Thermal mass, PCM and natural ventilation all need air circulation for optimum cooling performance, which is dependent on occupant behaviour.

Table 4.

Efficacy of passive cooling strategies against overheating factors.

Passive cooling measures		Occupancy	Dwelling type	Orientation	Construction	Weather
Heat and solar protection	Vegetation	Lacks robust evidence.	Medium^75,84	High^75,121	High^{75,84–87,122}	Medium^84,122
	Wall insulation	High^{44,48,49,62,63,91}	Medium¹⁶	High¹⁶	Medium^58,91	Medium⁶⁶
	Solar shading	Medium^49,62,94	High^15,16	Medium¹⁶	Low^{15,16,29,32,62,64,75,95}	Low^15,120
Heat modulation	Thermal mass	High¹²³	Medium⁷⁵	High⁷⁵	Medium^48,55,75,124	High^32,40,99,124
Heat modulation	PCM	High^102,125	Medium⁷⁵	High¹²⁶	Medium^{59,67,101,127}	High^{59,67,101–104}
Heat dissipation	Natural ventilation	High^{45,46,48–50,56,80,94}	High^16,75	High^16,75	High^40,75	High^{11,40,105,128}
Heat dissipation	Cool paint	Low¹²⁹	Medium^15,16,75,84	Low^16,75	High^15,16,75,84	Medium¹⁵

Vegetation

Vegetation is climate sensitive, and adequate rainfall as well as warm temperatures, are required for optimal performance.^84,122 Furthermore, its cooling effectiveness appears to vary substantially with different orientations,^75,121 most likely due to shadowing from surrounding structures. Previous studies did not adequately account for the effects of occupancy on vegetation’s cooling effectiveness. Occupants may water the plants or erect shading, which may affect the vegetation’s cooling performance. More research is therefore needed on the effects of human behaviour on the cooling performance of vegetation. Zinzi and Agnoli⁸⁴ revealed that green roofs’ cooling efficacy increases with more exposed surfaces, with a higher cooling potential for uninsulated dwellings.^{75,84–87,122}

Wall insulation

Occupant behaviour influences overheating risks in highly insulated dwellings owing to the variety of building operations, such as the use of solar shading and natural ventilation.^{44,48,49,62,63} Both van Hooff, Blocken and Hensen et al.⁷⁵ and Porrit, Cropper and Shao et al.¹⁶ showed significant variation in the performance of wall insulation with respect to different orientations. Figueiredo, Kämpf and Vicente⁶⁶ concluded that Passivhaus construction is a feasible concept in the Mediterranean climate, and Hidalgo, Millián and Psomas et al.⁶⁰ found that the investigated Passivhaus dwelling passed the TM52⁶¹ overheating criteria. Increasing insulation levels in UK dwellings can be a viable passive solution as the Mediterranean climate is now hotter than the temperate climate. Other passive strategies, like cool paint, may be needed to reduce overheating risks given greater insulation levels.

Solar shading

Despite its reliance on occupant behaviour,^49,62,94 Gupta and Gregg¹⁵ found external louvred shading to be the most effective passive strategy in the 2080s climate. Compared to terraced and detached dwellings, only flats had significant cooling variations in the cooling performance of solar shading,⁷⁵ whereas Gupta and Gregg¹⁵ found lower cooling effectiveness for flats and mid-terrace dwellings. This could be due to higher storey flats having higher solar heat gains than other dwelling types and fewer exposed surfaces to provide solar shading for mid-terrace dwellings. Similarly, Porrit, Cropper and Shao et al.¹⁶ found that external shutters were more effective in reducing overheating hours than fixed shading. In addition, they showed significant differences in the cooling performance of solar shading (e.g. fixed shading and external shutter) between end-terrace and mid-terrace dwellings. van Hooff, Blocken and Hensen et al.⁷⁵ used automated shading rather than fixed external shading, which could explain the similar cooling performance on the terraced and detached dwellings. In both well-insulated^{29,32,62,64,75,95} and traditional dwellings,^15,16,29 solar shading normally provides optimal cooling performance. However, overheating hours can vary greatly for different shading orientations¹⁶ as some are energy inefficient⁷⁰ or difficult to shade.^38,51–53

Thermal mass

Heat dissipation and modulation strategies are often influenced by occupants’ use of natural ventilation and external shading.¹²³ Sufficient air exchange is required to improve the cooling effectiveness of thermal mass. In addition, the use of nighttime ventilation to increase the cooling efficacy of thermal mass will become less effective as the climate warms, as not enough air exchanges can occur with the outside environment because of the lower temperature difference; this will reduce thermal mass’ cooling efficacy as the external temperature increases.^32,40,99,124 Moreover, previous studies have established the usefulness of thermal mass in well-insulated dwellings.^32,55

Phase change material

Ineffective ventilation strategies adopted by occupants can delay the solidification of PCM, affecting its cooling efficacy.¹²⁵ The use of PCMs has been shown to be effective in well-insulated dwellings to reduce overheating risks.^67,101,127 Furthermore, south and west orientations allow for optimal solidification cycles and sharp temperature fluctuations, respectively.¹²⁶ Information regarding the influence of different dwelling types on the cooling efficacy of PCM was scarce. Therefore, it is assumed that the influence of different dwelling types on the cooling efficacy of PCM would be similar to that of thermal mass due to their similar heat-modulating behaviours.

Natural ventilation

Several studies have found a significant association between occupant behaviour and using natural ventilation to decrease overheating risks.^{45,46,48–50,56,80,94} van Hooff, Blocken and Hensen et al.⁷⁵ found that the variation in the cooling effectiveness of natural ventilation for different orientations was modest for traditional dwellings and greater for insulated dwellings.^40,75 Porrit, Cropper and Shao et al.¹⁶ showed different cooling potentials achieved by natural ventilation for different orientations in traditional dwellings. It is worth noting that authors^16,75 employed different window opening strategies. Natural ventilation should be prioritised by occupants in highly insulated dwellings, given its reported importance.

Cool paint

The cooling efficiency of a cool roof may be enhanced by occupants adjusting the indoor environment’s temperature with respect to the cool roof’s cooling impact;¹²⁹ the cooling impact may be challenging to quantify precisely by occupants to adjust the indoor environment accordingly. Unlike cool walls, cool roofs are less sensitive to overheating in different orientations.¹⁶ Furthermore, dwellings with minimal insulation^75,84 and more exposed surfaces⁷⁵ benefit the most from cool paint. However, it is worth noting that Gupta and Gregg¹⁵ evaluated a combination of cool walls and roofs, and van Hooff, Blocken and Hensen et al.⁷⁵ did not specify whether cool roofs or walls were employed, simply that cool paint was applied to exterior surfaces.¹⁶

Conclusions and future works

The review identified that building design, construction and household characteristics are the most important factors influencing indoor overheating. There is a greater overheating risk in certain types of dwellings, such as flats and mid-terraced houses, as well as rooms that face south or west and other orientations in between. Due to the lower temperature threshold in the static overheating criterion, bedrooms are often more likely to be identified as overheated. Living rooms are typically warmer than bedrooms in flats, most likely due to greater heat gains from cooking in open-plan flats and higher solar heat gains. On the other hand, living rooms in houses are usually located on the ground floor and receive comparatively less solar heat gains than bedrooms on the first floor. The type and age of the dwelling, as well as the number of floors and floor area, may influence the difference in the internal temperature between bedrooms and living rooms.

Solid-walled constructions are less susceptible to overheating than well-insulated contemporary constructions. Therefore, the placement of wall insulation must be carefully considered because of the likely increased risk of overheating associated with internally placed insulation, given that a sizeable share of the UK housing stock still has solid-walled constructions. However, findings suggest that the increased risk of overheating caused by internal wall insulation can be avoided in the current and possibly future climate with additional passive strategies such as external solar shading, which can offer optimal cooling efficacy in well-insulated constructions. On the other hand, cool paint has been found to be the ideal passive strategy to reduce overheating in uninsulated dwellings. However, more research would be beneficial on the occupancy influence on cool paints’ cooling efficacy.

Occupant-adopted ventilation strategies such as the frequency and duration of opening windows and air provision by mechanical ventilation significantly influence the internal temperature. Occupant characteristics can exacerbate overheating risks, for example, the elderly and infirm are particularly vulnerable to indoor overheating when there is inadequate ventilation control. Planning for efficient heat dissipation without occupant involvement by developing an intelligent ventilation system is a feasible solution to reduce the overheating risk for the elderly. Further research could consider recent advances in generative design such as generative adversarial networks to generate prototype floor layouts and optimise indoor environments using a representative internal heat gain profile for the elderly, considering various dwelling configurations and settings.

The modelling of occupants in overheating studies is challenging due to their stochastic nature and inherent uncertainties in their behaviour related to the indoor environmental performance. Further monitoring studies should be conducted to quantify the relationships between occupant characteristics and the indoor environment with a view to enhance modelling techniques. Recent developments in probabilistic and agent-based modelling can help with the realistic representation of occupants in a model. The following passive strategies can benefit from a more accurate representation of occupants in modelling studies: vegetation, since there is little research on how occupants affect vegetation’s ability to cool; and thermal mass and natural ventilation, both of which are significantly influenced by occupant behaviour. Furthermore, most overheating studies use thermal comfort models drawn from workplace settings and adaptation opportunities, which may not be representative of the circumstances found in dwellings. Therefore, the development of a domestic thermal comfort model able to account for the variations in buildings, systems and occupant characteristics can be helpful.

Passive cooling strategies need to be coupled in the 2080s to effectively limit the risk of overheating as they become less effective as the climate warms. More research is needed to fully understand the usage of various passive cooling strategies in well-insulated contemporary dwellings.

Footnotes

Authors’ contribution

All authors contributed equally in the preparation of this manuscript.

Declaration of conflicting interests

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Mousa Alrasheed

Monjur Mourshed

Appendix

The risk of overheating can be assessed using thermal comfort models. Thermal comfort criteria can be classified as static and adaptive models. Adaptive models in CIBSE TM52 consider adaptive measures taken by occupants, but static models, such as in CIBSE Guide A, do not. On the other hand Passivhaus criteria is designed specifically for the assessment of Passivhaus dwellings.

CIBSE Guide A²⁸ overheating criteria:

• For living rooms, 1% of total hours of occupation annually above 28°C.

• For bedrooms, 1% of total hours of occupation annually above 26°C.

BS EN 15251¹³⁰ adaptive comfort criteria:

Thermal discomfort is linked to the difference between operative temperature T_op and comfort temperature T_c, which is given by Equation (1) (1)

T_{c} (° C) = 0.33 T_{r m} + 18.8

where (2)

T_{r m} (° C) = (T_{o d - 1} + 0.8 T_{o d - 2} + 0.6 T_{o d - 3} + 0.5 T_{o d - 4} + 0.4 T_{o d - 5} + 0.3 T_{o d - 6} + 0.2 T_{o d - 7}) / 3.8

• $T_{o d - 1}$ is the daily average of the external temperature for the day before.

• $T_{o d - 2}$ is the daily average of the external temperature for 2 days before.

Adaptive criteria assessment has two building categories: CAT I and CAT II. CAT I is for occupied dwellings while CAT II is for unoccupied dwellings. Both provide temperature-adaptive limits. For each dwelling type, BS EN1251 determines the likelihood of overheating. Here are the upper and lower limits (3)

T_{\min} (° C) = 0.33 T_{r m} + 16.8

(4)

T_{\max} (° C) = 0.33 T_{r m} + 20.8

(5)

T_{\min} (° C) = 0.33 T_{r m} + 15.8

(6)

T_{\max} (° C) = 0.33 T_{r m} + 21.8

CIBSE TM52⁶¹:

The maximum temperature values in equations (4) and (6) are from BS EN15251. Using such a model, CIBSE TM52 presented three criteria, two of which must fail to indicate overheating in a thermal zone. The CIBSE TM52 criteria are as follows:

• Exceeding number of hours (H_e): The total number of exceeding hours H_e where difference $∆ T$ between operating temperature $T_{o p}$ and maximum allowable temperature $T_{\max}$ is above 1°C for more than 3% of total occupied hours.

• The severity of overheating: For each day during cooling season, the weighted exceedance (W_e) for every degree °C above the maximum allowable $T_{\max}$ is equal to or less than 6.

• Criteria 3, upper temperature limit $T_{u p p}$ : $∆ T$ to not exceed 3°C

F o r C A T I I : T_{u p p} (° C) = T_{c o m f} + 7 ° C

CIBSE TM59²⁷:

Any type of building can be accounted for with CIBSE TM52, while CIBSE TM59 has been amended to account for dwellings, specifically flats or large complexes. If one of the two criteria adopted is not met, CIBSE TM59 assumes overheating risk exists. It includes the first criterion from CIBSE TM52 and the bedroom criterion from CIBSE Guide A.

Passivhaus Trust²⁶:

• At the whole building level, temperatures above 25°C to not exceed more than 10% of occupied hours.

• For good practice, 5% is used as the exceedance limit for occupied hours above 25°C.

References

Defra . Defra’s climate change plan 2010. London UK: Department for Environment Food and Rural Affairs, 2010.

Langevin

Reyna

Ebrahimigharehbaghi

Sandberg

Fennell

Nägeli

Laverge

Delghust

Mata

Van Hove

Webster

Federico

Jacob

Camarasa

. Developing a common approach for classifying building stock energy models. Renew Sustain Energ Rev 2020; 133: 110276. DOI: 10.1016/j.rser.2020

Department for Business, Energy and Industrial Strategy . 2020 UK greenhouse gas emissions, final figures. London UK: Department for Business, Energy and Industrial Strategy, 2022.

Zero Carbon Hub (ZCH) . Overheating in homes: an introduction for planners, designers and property owners. London UK: Zero Carbon Hub (ZCH), 2015.

Adlington

Ceranic

. A critical review of the impact of overheating in buildings using matrix framework assessment. In: Proceedings of the 7th Global Conference on Global Warming (GCGW-2018), Izmir, Turkey, 24-28 June 2018. DOI: 10.1999/1307-6892/63800.

Beizaee

Lomas

Firth

. National survey of summertime temperatures and overheating risk in English homes. Building Environ 2013; 65: 1–17.

Lomas

Kane

. Summertime temperatures and thermal comfort in UK homes. Build Res Info 2013; 41: 259–280.

Pathan

Mavrogianni

Summerfield

Oreszczyn

Davies

. Monitoring summer indoor overheating in the London housing stock. Energ Build 2017; 141: 361–378. DOI: 10.1016/j.enbuild.2017.02.049

Symonds

Taylor

Chalabi

Mavrogianni

Davies

Hamilton

Vardoulakis

Heaviside

Macintyre

. Development of an England-wide indoor overheating and air pollution model using artificial neural networks. J Build Perform Simul 2016; 9: 606–619.

10.

Brotas

Nicol

. The problem of overheating in European dwellings. In: 9th International Windsor Conference, Windsor Park, UK, 7765-10781 april 2016.

11.

Hamdy

Carlucci

Hoes

Hensen

JLM

. The impact of climate change on the overheating risk in dwellings—A Dutch case study. Build Environ 2017; 122: 307–323. DOI: 10.1016/j.buildenv.2017.06.031

12.

Committee on Climate Change (CCC) . Synthesis report: priorities for the next five years. London, UK: Committee on Climate Change 2017.

13.

Dodoo

Gustavsson

. Energy use and overheating risk of Swedish multi-storey residential buildings under different climate scenarios. Energy 2016; 97: 534–548.

14.

Mavrogianni

Wilkinson

Davies

Biddulph

Oikonomou

. Building characteristics as determinants of propensity to high indoor summer temperatures in London dwellings. Build Environ 2012; 55: 117–130.

15.

Gupta

Gregg

. Using UK climate change projections to adapt existing English homes for a warming climate. Build Environ 2012; 55: 20–42.

16.

Porritt

Cropper

Shao

Goodier

. Ranking of interventions to reduce dwelling overheating during heat waves. Energ Build 2012; 55: 16–27.

17.

Gupta

Kapsali

. Evaluating the ‘as-built’ performance of an eco-housing development in the UK. Build Serv Eng Res Technol 2016; 37: 220–242.

18.

Robine

Cheung

SLK

Le Roy

Van Oyen

Griffiths

Michel

Hermann

. Death toll exceeded 70,000 in Europe during the summer of 2003. C R Biol 2008; 331: 171–178.

19.

Kosatsky

. The 2003 European heat waves. Euro Surveill 2005; 10(7): 148–149.

20.

Johnson

Kovats

McGregor

Stedman

Gibbs

Walton

. The impact of the 2003 heat wave on daily mortality in England and Wales and the use of rapid weekly mortality estimates. Euro Surveill 2005; 10: 168–171.

21.

UK Health Security Agency, Department of Health and Social Care, and NHS England . Heatwave plan for England. London, UK: UK Health Security Agency, Department of Health and Social Care, and NHS England, 2014.

22.

World Health Organization (WHO) . Improving public health responses to extreme weather/heatwaves: EuroHEAT, Meeting report, Bonn, Germany, 22-23 March 2009., . 1–70.

23.

Oikonomou

Davies

Mavrogianni

Biddulph

Wilkson

Kolokotroni

. Modelling the relative importance of the urban heat island and the thermal quality of dwellings for overheating in London. Build Environ 2012; 57: 223–238.

24.

Hajat

Kovats

Lachowycz

. Heat-related and cold-related deaths in England and Wales: Who is at risk? Occup Environ Med 2007; 64: 93–100.

25.

Pullin

Stewart

. Guidelines for systematic review in conservation and environmental management. Conservation Biol 2006; 20: 1647–1656.

26.

Passivhaus Trust . Passivhaus UK buildings database. London, UK: Passivhaus Trust, 2018.

27.

Chartered Institution of Building Services Engineers CIBSE TM59 . Design Methodology for the assessment of overheating risk in homes. London: The Chartered Institution of Building Services Engineers, 2017.

28.

Chartered Institution of Building Services Engineers (CIBSE) . CIBSE Guide A: environmental design. London, UK: Chartered Institute of Building Services Engineers, 2006.

29.

Tink

Porritt

Allinson

Loveday

. Measuring and mitigating overheating risk in solid wall dwellings retrofitted with internal wall insulation. Build Environ 2018; 141: 247–261.

30.

Hulme

Beaumont

Summers

. Energy follow-up survey 2011, report 7: thermal comfort & overheating. Watford, UK: Building Research Establishment (BRE), 2017.

31.

Dengel

Swainson

. Overheating in new homes A review of the evidence. Milton Keynes, UK: NHBC Foundation, 2012.

32.

McLeod

Hopfe

Kwan

. An investigation into future performance and overheating risks in Passivhaus dwellings. Build Environ 2013; 70: 189–209.

33.

Kinnane

Grey

Dyer

. Adaptable housing design for climate change adaptation. Proc Inst Civil Eng 2017; 170: 249–267.

34.

Sharifi

Saman

Alemu

. Identification of overheating in the top floors of energy-efficient multilevel dwellings. Energy Build 2019; 204: 109452. DOI: 10.1016/j.enbuild.2019.109452

35.

Nicol

Roys

Ormandy

Ezratty

. The cost of poor housing in the European Union. Watford, UK: Building Research Establishment (BRE), 2016.

36.

Georgiadou

Hacking

Guthrie

. Future-proofed energy design for dwellings: case studies from England and application to the code for sustainable homes. Build Serv Eng Res Technol 2013; 34: 9–22.

37.

Gupta

Gregg

Williams

. Cooling the UK housing stock post-2050s. Build Serv Eng Res Technol 2015; 36: 196–220.

38.

Gupta

Gregg

. Assessing the magnitude and likely causes of summertime overheating in modern flats in UK. Energies 2020; 13(19): 5202. DOI: 10.3390/en13195202

39.

Wright

Young

Natarajan

. Dwelling temperatures and comfort during the August 2003heat wave. Build Serv Eng Res Technol 2005; 26: 285–300.

40.

Peacock

Jenkins

Kane

. Investigating the potential of overheating in UK dwellings as a consequence of extant climate change. Energ Policy 2010; 38: 3277–3288. DOI: 10.1016/j.enpol.2010.01.021

41.

Meinke

Hawighorst

Wagner

Trojan

Schweiker

. Comfort-related feedforward information: occupants’ choice of cooling strategy and perceived comfort. Build Res Info 2017; 45: 222–238.

42.

Murtagh

Gatersleben

Fife-Schaw

. Occupants’ motivation to protect residential building stock from climate-related overheating: a study in southern England. J Clean Prod 2019; 226: 186–194.

43.

Department for Communities and Local Government . Investigation into overheating in homes. London, UK: AECOM, 2012.

44.

Fletcher

Johnston

Glew

Parker

. An empirical evaluation of temporal overheating in an assisted living Passivhaus dwelling in the UK. Build Environ 2017; 121: 106–118.

45.

Vellei

Ramallo-González

Coley

Lee

Gabe-Thomas

Lovett

Natarajan

. Overheating in vulnerable and non-vulnerable households. Build Res Info 2017; 45: 102–118.

46.

Petrou

Symonds

Mavrogianni

Mylona

Davies

. The summer indoor temperatures of the English housing stock: exploring the influence of dwelling and household characteristics. Build Serv Eng Res Technol 2019; 40: 492–511.

47.

Ozarisoy

Elsharkawy

. Assessing overheating risk and thermal comfort in state-of-the-art prototype houses that combat exacerbated climate change in UK. Energ Build 2019; 187: 201–217.

48.

Morgan

Foster

Poston

Sharpe

. Overheating in Scotland: contributing factors in occupied homes. Build Res Info 2017; 45: 143–156.

49.

Ridley

Bere

Clarke

Schwartz

Farr

. The side by side in use monitored performance of two passive and low carbon Welsh houses. Energ Build 2014; 82: 13–26.

50.

Baborska-Narożny

Stevenson

Grudzińska

. Overheating in retrofitted flats: occupant practices, learning and interventions. Build Res Info 2017; 45: 40–59.

51.

Kolokotroni

Zhang

Watkins

. The London Heat Island and building cooling design. Solar Energy 2007; 81: 102–110.

52.

Gupta

Gregg

. Preventing the overheating of English suburban homes in a warming climate. Build Res Info 2013; 41: 281–300.

53.

Mitchell

Natarajan

. Overheating risk in Passivhaus dwellings. Build Serv Eng Res Technol 2019; 40(4): 446–469.

54.

Jones

Goodhew

De Wilde

. Measured indoor temperatures, thermal comfort and overheating risk: post-occupancy evaluation of low energy houses in the UK. Energy Procedia 2016; 88: 714–720.

55.

Hacker

Belcher

Connell

. Beating the heat: keeping UK building cool in a warming climate. Phys Teach 2005; 16: 175.

56.

Toledo

Cropper

Wright

. Unintended consequences of sustainable architecture: Evaluating overheating risks in new dwellings. In: Passive and Low Energy Architecture Conference – 32nd International Conference on Passive and Low Energy Architecture. Cities, Buildings, People: Towards Regenerative Environments. Los Angeles, USA, 11–13 July 2016.

57.

Orme

Palmer

. Control of overheating in future housing - design guidance for low energy strategies. Hertfordshire UK: Faber Maunsell Ltd, 2003.

58.

Willand

Ridley

Pears

. Relationship of thermal performance rating, summer indoor temperatures and cooling energy use in 107 homes in Melbourne, Australia. Energ Build 2016; 113: 159–168.

59.

Sajjadian

Lewis

Sharples

. The potential of phase change materials to reduce domestic cooling energy loads for current and future UK climates. Energ Build 2015; 93: 83–89.

60.

Hidalgo

García-Gáfaro

Heiselberg

Millán

. Overheating Assessment of a Passive House Case Study in Spain and operational optimization. In:Effective ventilation in high performance buildings: 36th AIVC Conference, Madrid, Spain, 23-24 September 2015; 645–655.

61.

Chartered Institute of Building Services Engineers CIBSE TM52 . The limits of thermal comfort: Avoiding overheating in European buildings. London UK: The Chartered Institution of Building Services, 2013.

62.

Ridley

Clarke

Bere

Altamirano

Lewis

Durdev

Farr

. The monitored performance of the first new London dwelling certified to the passive house standard. Energy Build 2013; 63: 67–78.

63.

Tabatabaei Sameni

Gaterell

Montazami

Ahmed

. Overheating investigation in UK social housing flats built to the passivhaus standard. Build Environ 2015; 92: 222–235.

64.

Mlakar

Štrancar

. Overheating in residential passive house: solution strategies revealed and confirmed through data analysis and simulations. Energ Build 2011; 43: 1443–1451.

65.

Colclough

Kinnane

Hewitt

Griffiths

. Investigation of nZEB social housing built to the passive house standard. Energ Build 2018; 179: 344–359.

66.

Figueiredo

Kämpf

Vicente

. Passive house optimization for Portugal: overheating evaluation and energy performance. Energ Build 2016; 118: 181–196.

67.

Sage-Lauck

Sailor

. Evaluation of phase change materials for improving thermal comfort in a super-insulated residential building. Energ Build 2014; 79: 32–40.

68.

Dan

Tanasa

Stoian

Brata

Stoian

Nagy Gyorgy

Florut

. Passive house design-An efficient solution for residential buildings in Romania. Energ Sustain Develop 2016; 32: 99–109.

69.

Espinosa

Symonds

Petrou

. Modelling the influence of layout on overheating risk of London flats institute of environmental design and engineering. In: Buildings Simulation Conference Proceeding, Rome, Italy, 7 April 2019.

70.

Habitzreuter

Smith

Keeling

. Modelling the overheating risk in an uniform high-rise building design with a consideration of urban context and heatwaves. Indoor Built Environ 2020; 29: 671–688.

71.

Gupta

Gregg

Bruce-Konuah

. Assessing the occurrence of summertime overheating in occupied and unoccupied low energy homes. In: Proceedings of 33rd PLEA International Conference: Design to Thrive, PLEA, Edinburgh, Scotland, 26 October 2017; 3: 3778–3785.

72.

Mourkos

McLeod

Hopfe

Goodier

Swainson

. Assessing the application and limitations of a standardised overheating risk-assessment methodology in a real-world context. Build Environ 2020; 181: 107070.

73.

Fitton

Swan

Webster

. Assessing overheating of the UK existing dwellings - A case study of replica Victorian end terrace house. Build Environ 2014; 77: 1–11.

74.

Firth

Wright

. Investigating the thermal characteristics of English dwellings: summer temperatures. In: Proceedings of Conference: Air Conditioning and the Low Carbon Cooling Challenge - Windsor 2008 Conference, London, UK, 27-29 July 2008.

75.

van Hooff

Blocken

Hensen

JLM

Timmermans

HJP

. On the predicted effectiveness of climate adaptation measures for residential buildings. Build Environ 2014; 82: 300–316.

76.

Capon

Hacker

. Modelling climate change adaptation measures to reduce overheating risk in existing dwellings. In: IBPSA 2009-International Building Performance Simulation Association, Glasgow, Scotland, 27-30 July 2009; 1276–1283.

77.

Mavrogianni

Taylor

Davies

Thoua

Kolm-Murray

. Urban social housing resilience to excess summer heat. Build Res Info 2015; 43: 316–333.

78.

Quigley

Lomas

. Performance of lightweight apartment buildings during a heat wave. Proc 10th Windsor Conf: Rethinking Comfort 2018: 32–47.

79.

Taylor

Symonds

Wilkinson

Heaviside

Macintyre

Davies

Mavrogianni

Hutchinson

. Estimating the influence of housing energy efficiency and overheating adaptations on heat-related mortality in the West Midlands, UK. Atmosphere 2018; 9: 1–17.

80.

Mavrogianni

Pathan

Oikonomou

Biddulph

Symonds

Davies

. Inhabitant actions and summer overheating risk in London dwellings. Build Res and Info 2017; 45: 119–142. DOI: 10.1080/09613218.2016.1208431

81.

McGill

Sharpe

Robertson

Gupta

Mawditt

. Meta-analysis of indoor temperatures in new-build housing. Build Res Info 2017; 45: 19–39.

82.

Department for Business, Energy and industrial strategy . Energy follow up survey: thermal comfort, damp and ventilation final report. London UK: Department for Business, Energy and Industrial Strategy, 2017.

83.

Al-Obaidi

Ismail

Abdul Rahman

. Passive cooling techniques through reflective and radiative roofs in tropical houses in Southeast Asia: a literature review. Front Arch Res 2014; 3: 283–297.

84.

Zinzi

Agnoli

. Cool and green roofs. An energy and comfort comparison between passive cooling and mitigation urban heat island techniques for residential buildings in the Mediterranean region. Energy Build 2012; 55: 66–76.

85.

Gagliano

Detommaso

Nocera

Patania

Aneli

. The retrofit of existing buildings through the exploitation of the green roofs - A simulation study. Energy Procedia 2014; 62: 52–61.

86.

Virk

Jansz

Mavrogianni

Mylona

Stocker

Davies

. The effectiveness of retrofitted green and cool roofs at reducing overheating in a naturally ventilated office in London: direct and indirect effects in current and future climates. Indoor Built Environ 2014; 23: 504–520.

87.

Castleton

Stovin

Beck

SBM

Davison

. Green roofs; building energy savings and the potential for retrofit. Energ Build 2010; 42: 1582–1591.

88.

Emmanuel

Loconsole

. Green infrastructure as an adaptation approach to tackling urban overheating in the Glasgow Clyde Valley Region, UK. Landsc Urban Plan 2015; 138: 71–86.

89.

Laureti

Martinelli

Battisti

. Assessment and mitigation strategies to counteract overheating in urban historical areas in Rome. Climate 2018; 6(1): 18. DOI: 10.3390/cli6010018

90.

Battista

de Lieto Vollaro

Zinzi

. Assessment of urban overheating mitigation strategies in a square in Rome, Italy. Solar Energ 2019; 180: 608–621.

91.

Hamdy

Hasan

Siren

. Applying a multi-objective optimization approach for Design of low-emission cost-effective dwellings. Build Environ 2011; 46: 109–123.

92.

Mavrogianni

Davies

Taylor

Oikonomou

. The unintended consequences of energy efficient retrofit on indoor air pollution and overheating risk in a typical Edwardian mid-terraced house. In: FutureBuild – International Conference, Bath, UK, 4–6 September 2013.

93.

Tillson

Oreszczyn

Palmer

. Assessing impacts of summertime overheating: some adaptation strategies. Build Res Info 2013; 41(6): 652–661. DOI: 10.1080/09613218.2013.808864

94.

Mavrogianni

Davies

Taylor

Chalabi

Biddulph

Oikonomou

Das

Jones

. The impact of occupancy patterns, occupant-controlled ventilation and shading on indoor overheating risk in domestic environments. Build Environ 2014; 78: 183–198.

95.

Psomas

Heiselberg

Duer

Bjørn

. Overheating risk barriers to energy renovations of single family houses: multicriteria analysis and assessment. Energy Build 2016; 117: 138–148.

96.

Alders

. Adaptive heating, ventilation and solar shading for dwellings. Archit Sci Rev 2017; 60: 150–166.

97.

Birchmore

Davies

Etherington

Tait

Pivac

. Overheating in Auckland homes: testing and interventions in full-scale and simulated houses. Build Res Info 2017; 45: 157–175.

98.

GrussaDe

Andrews

Lowry

Newton

Yiakoumetti

Chalk

Bush

D. A

. London residential retrofit case study: evaluating passive mitigation methods of reducing risk to overheating through the use of solar shading combined with night-time ventilation. Build Serv Eng Res Technol 2019; 40: 389–408.

99.

Jimenez-Bescos

. An evaluation on the effect of night ventilation on thermal mass to reduce overheating in future climate scenarios. Energ Procedia 2017; 122: 1045–1050.

100.

Saffari

de Gracia

Ushak

Cabeza

. Passive cooling of buildings with phase change materials using whole-building energy simulation tools: a review. Renew Sustain Energ Rev 2017; 80: 1239–1255.

101.

Auzeby

Wei

Underwood

Tindall

Chen

Ling

Buswell

. Effectiveness of using phase change materials on reducing summer overheating issues in UK residential buildings with identification of influential factors. Energies 2016; 9: 605–620. DOI: 10.3390/en9080605

102.

Fernandes

NTA

Costa

VAF

. Use of phase change materials as passive elements for climatization purposes in summer the Portuguese case. Int J Green Energ 2009; 6: 302–311.

103.

Ascione

Bianco

De Masi

de’Rossi

Vanoli

. Energy refurbishment of existing buildings through the use of phase change materials: energy savings and indoor comfort in the cooling season. Appl Energ 2014; 113: 990–1007.

104.

Baniassadi

Sailor

Bryan

. Effectiveness of phase change materials for improving the resiliency of residential buildings to extreme thermal conditions. Solar Energ 2019; 188: 190–199.

105.

Shikder

Mourshed

Price

. Summertime impact of climate change on multi-occupancy British dwellings. Open House Int 2012; 37: 50–60.

106.

Weng

. Performance of UK dwellings in projected future climates. Energ Procedia 2017; 105: 3727–3732.

107.

Roetzel

Tsangrassoulis

Dietrich

Busching

. A review of occupant control on natural ventilation. Renew Sustain Energ Rev 2010; 14: 1001–1013.

108.

Zhang

Mohegh

Levinson

Ban-Weiss

. Systematic comparison of the influence of cool wall versus cool roof adoption on urban climate in the Los Angeles basin. Environ Sci Technol 2018; 52: 11188–11197.

109.

Garshasbi

Haddad

Paolini

Santamouris

Papangelis

Dandou

Methymaki

Portalakis

Tombrou

. Urban mitigation and building adaptation to minimize the future cooling energy needs. Solar Energ 2020; 204: 708–719.

110.

Synnefa

Santamouris

. Advances on technical, policy and market aspects of cool roof technology in Europe: the cool roofs project. Energy Build 2012; 55: 35–41.

111.

Pisello

Cotana

. The thermal effect of an innovative cool roof on residential buildings in Italy: results from two years of continuous monitoring. Energ Build 2014; 69: 154–164.

112.

Gentle

Aguilar

JLC

Smith

. Optimized cool roofs: integrating albedo and thermal emittance with R-value. Solar Energ Mater Solar Cells 2011; 95: 3207–3215.

113.

Barozzi

Pollastro

. Assessment of the impact of cool roofs in temperate climates through a comparative experimental campaign in outdoor test cells. Buildings 2016; 6(4): 1–18.52.

114.

Zinzi

Fasano

. Properties and performance of advanced reflective paints to reduce the cooling loads in buildings and mitigate the heat island effect in urban areas. Intern Journ Sustain Energy 2009; 28: 123–139.

115.

Lee

Steemers

. Exposure duration in overheating assessments: a retrofit modelling study. Build Res Info 2017; 45: 60–82.

116.

Banihashemi

Maderspacher

Brasche

Lang

. Effectiveness of passive climate adaptation measures in residential buildings in Germany. In: Proceedings of 33rd PLEA International Conference: Design to Thrive, Edinburgh, UK, July 2017.

117.

Chvatal

KMS

Corvacho

. The impact of increasing the building envelope insulation upon the risk of overheating in summer and an increased energy consumption. J Build Perform Simul 2009; 2: 267–282.

118.

Adekunle

Nikolopoulou

. Thermal comfort, summertime temperatures and overheating in prefabricated timber housing. Build Environ 2016; 103: 21–35.

119.

Ibrahim

Pelsmakers

SLJ

. Low-energy housing retrofit in North England: overheating risks and possible mitigation strategies. Build Serv Eng Res Technol 2018; 39: 161–172.

120.

Gupta

. Using a simulation based approach to adapt the designs of zero carbon homes against a warming climate. Oxford, UK: CIBSE Technical Symposium, 2013.

121.

Haak

AJC.

Climate change and heat stress in residential buildings: evaluation of adaptation measures. Masters Thesis. Eindhoven, Netherlands: Eindhoven University of Technology, 2012, pp. 1–99.

122.

Ziogou

Michopoulos

Voulgari

Zachariadis

. Implementation of green roof technology in residential buildings and neighborhoods of Cyprus. Sustain Cities Soc 2018; 40: 233–243.

123.

Kuczyński

Staszczuk

Gortych

Stryjski

. Effect of thermal mass, night ventilation and window shading on summer thermal comfort of buildings in a temperate climate. Build Envir 2021; 204: 108126.

124.

Mulville

Stravoravdis

. The impact of regulations on overheating risk in dwellings. Build Res Information 2016; 44: 520–534.

125.

Guarino

Athienitis

Cellura

Bastien

. PCM thermal storage design in buildings: experimental studies and applications to solaria in cold climates. Appl Energ 2017; 185: 95–106.

126.

Berardi

Soudian

. Experimental investigation of latent heat thermal energy storage using PCMs with different melting temperatures for building retrofit. Energ Build 2019; 185: 180–195.

127.

Figueiredo

Vicente

Oliveira

Rodrigues

Samagaio

. Multiscale modelling approach targeting optimisation of PCM into constructive solutions for overheating mitigation in buildings. Appl Sci 2020; 10: 1–16.

128.

Kalogirou

Panayiotou

Koukkouli

Gelegenis

. Night-time ventilation for passive cooling of dwellings: a case study for cyprus. In: EuroSun, Graz, Austria, 28 September–01 October 2010.

129.

Pisello

Piselli

Cotana

. Influence of human behaviour on cool roof effect for summer cooling. Build Environ 2015; 88: 116–128.

130.

BS EN 15251: 2007 . Indoor and environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics, 2007. London, UK: British Standards Institution.