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Persistent URL http://purl.org/net/epubs/work/25580
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Record Id 25580
Title On the local constitutive and directed graph network representations of response factors
Abstract Many of the calculation procedures for determining the thermal transport through building walls are based on thermostat directed graph networks. These procedures relate the heat flux and temperature in one region of the wall to the heat flux and temperature in another region of the wall. Recently an ASHRAE sponsored project examined the ability of such procedures to correctly predict the performance of a number of wall types. That study showed indicated that the design calculations were only accurate to the 50% level. A thermal transport processes can be represented in either a local constitutive convolution form or as a directed graph network form. Both the local constitutive convolution and network representations are based on response factors which can, in principle, be used to estimate dynamic thermal transmission of the building components. The purpose of this paper is to show that only the local constitutive equations yield, for all cases, consistent and accurate values for the physical properties of the materials under test, whereas the directed graph network representations are unreliable. This is because the network representations are ill posed and are likely to lead to erroneous predictions in designing the performance of buildings. The constitutive representation allows the measurement of thermal conductivity and transmission of building components under real meteorological conditions. It is then used to measure the convective and radiative coefficients of a wall and the representation can be extended to the nonlinear thermal transport case.
Organisation SERC
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Language English (EN)
Type Details URI(s) Local file(s) Year
Report RAL Technical Reports RAL-93-075. 1993. RAL-TR-1993-075.pdf 1993