The point-source model, the most simplified version of the original model developed by Perez to estimate irradiances and illuminances on tilted planes, has been assessed using values of mean hourly illuminance obtained during a period of 14 consecutive months at Madrid. When the model is used to fit data for all the vertical surfaces facing north, east, south and west, it performs better with local coefficients than with those given by Perez. The model's accuracy is considerably increased by the use of local coefficients derived independently for each orientation. In this case if coefficients are obtained separately for the data obtained when the surface 'sees' or does not 'see' the sun, a further, though smaller, increase in accuracy results.
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References
1.
Klucher T.M.Evaluation of models to predict insolation on tilted surfaces Solar Energy 23 111-114 (1979)
2.
Hay J.E. and McKay D.C.Calculation of solar irradiance for inclined surfaces : Verification of models which use hourly and daily data IEA Solar Heating and Cooling Program, Task IX final report (Downsview, Ontario , Canada: Atmospheric Environment Service) (1987)
3.
Gueymard C.An isotropic solar irradiance model for tilted surfaces and its comparison with selected engineering algorithms Solar Energy38367-386( 1987)
4.
Perez R., Stewart R., Arbogast C., Seals R. and Scott J.An anisotropic hourly diffuse radiation model for sloping surfaces: Description, performance validation, site dependency evaluation Solar Energy36487-497 (1986)
5.
Perez R., Seals R., Ineichen P., Stewart R. and Menicucci D.A new simplified version of the Perez diffuse irradiance model for tilted surfaces Solar Energy39221-231 (1987)
6.
Robbins C.L.Daylighting (New York: Van Nostrand Reinhold) (1984)
7.
Littlefair P.J.Daylight availability for lighting controls Proc. CIBSE National Lighting Conf. pp215-233 (1984)
8.
Oteiza P. and Soler A.A.comparison of the daylighting performance of different shading devices giving the same solar protectionArch. Sci. Rev. 38(4) 171-176 (1995)
9.
Compagnon R.Simulations numeriques de systemes d'eclairage naturel a penetration laterale Doctoral thesis, EPF, Lausanne (1993)
10.
Hunt D R GAvailability of daylight ( Garston: Building Research Establishment) (1979)
11.
International Energy AgencyTechnical reports on task 17 Vol. 2 ( 1995)
12.
Perez R., Ineichen P., Seals R., Michalsky J. and Stewart R.Modeling daylight availability and irradiance components from direct and global irradiance Solar Energy44271-289 (1990)
13.
Haves P. and Littlefair P.J.Daylight in dynamic thermal modeling programs : A lighting facility for SERI-RES BuildingServ. Eng. Res. Technol. 9183-188 (1988)
14.
Muneer T. and Angus R.C.Daylight illuminance models for the United Kingdom LightingRes. Technol. 25113-123 (1993)
15.
Littlefair P.J.Measurements of the luminous efficacy of daylight LightingRes. Technol. 20177-188 (1988)
16.
Olseth J.A. and Skartveit A.Observed and modeled hourly luminous efficacies under arbitrary cloudinessSolar Energy42221-233 (1989)
17.
Molineaux B. , Ineichen P. and Delaunay J.J.Direct luminous efficacy and atmospheric turbidity Improving model performanceSolar Energy (1994) (to be published)
18.
Nakamura H., Oki M., Hayashi Y. and Iwata T.The mean sky composed depending on the absolute luminance values of the sky elements and its application to daylighting predictionProc. Int. Daylighting Conf Long Beach, USA (1986)
19.
Perraudeau M.Climat lumineux a Nantes; Resultats de 15 mois des mesures (Nantes: CSTB) (1988)
20.
Perez R., Seals R. and Michalsky J.An all-weather model for sky luminance distribution Solar Energy50235-245 (1993)
21.
Kittler R. and Valko P.Radiance distribution on densely overcast skies: Comparison with CIE luminance standard Solar Energy51349-355 (1993)
22.
Littlefair P.J.A comparison of sky luminance models with measured data from Garston, United Kingdom Solar Energy53315-322 (1994)
23.
Kasten F.A new table and approximate formula for relative optical air mass Arch. Meteorol . Geophys. Bioklimatol. Ser. B14206-223 (1966)
24.
Kitler R., Hayman S., Ruck N. and Julian W.Daylight measurement data: Methods of evaluation and representation LightingRes. Technol. 24173-187(1992)
25.
Utrillas M.P. and Martinez-Lozano J.A.Performance evaluation of several versions of the Perez tilted diffuse irradiance modelSolar Energy53155-162(1994)
26.
Gómez V., Casanovas A., Utrillas M.P. and Martinez-Lozano J.Determination of Perez solar diffuse irradiance model coefficients for Valencia (Spain)Proc. 2nd World Renewable Energy Cong. pp2746-2750 (1992)
