Measuring and Analyzing Frequency Responses of Heat Conduction in Nanjing Buildings under In Situ Conditions

Abstract

In this paper we present in-situ measurements of the thermal characteristics of buildings in Nanjing, including information about the test chamber and arrangement of measuring points as well as measurement results, taken in Nanjing during the summer of 2001. A method for the analysis of in situ data is also presented that involves calculating frequency responses of heat conduction in buildings under in situ conditions. The main conclusions are as follows: For the zeroth and the first-order response of the frequency responses of heat conduction in buildings, the measured values match very well with theoretical values; therefore, it is possible to apply this analytical method in practical situations. However, the values measured were lower than the theoretical values, primarily, it was thought, because the tested buildings might not be dry enough; they might be affected by thermal bridges, and/or the un-controlled climate could affect measurements under field conditions. For the second-order response, the difference between the test values and theoretical values was too large to be accepted. Therefore, it was concluded that it was too difficult to measure accurately the second-order response of the frequency responses of heat conduction in buildings under in situ conditions. However, for the decay rate of the first-order response, values have already reached 20 times those needed to meet the requirements of engineering plans. We conclude, it is advisable to calculate the frequency responses of heat conduction in buildings under in situ conditions using the first-order response.