In situ assessment of the fabric and energy performance of five conventional and non-conventional wall systems using comparative coheating tests

Abstract

Comparative coheating tests have been carried out in five test buildings with walls constructed of Concrete Block Masonry and timber framed Hemp-lime composite, Polyisocyanurate (PIR), Wood Fibre and Mineral Wool. Five different methods of determining heat loss coefficient (HLC) were applied during the data analysis. While some variability in HLC values was observed between the different forms of construction, the hierarchy of HLC values among the test buildings were consistent, with the Concrete Block Masonry exhibiting the highest and Wood Fibre test building exhibiting the lowest HLC values. Except for the Concrete Block Masonry, there was good agreement between the calculated HLC values and those derived by applying the method 5 where the analysis incorporated both the effects of solar radiation and thermal mass. The in-situ U-value for the Concrete Block wall, determined by the average method, was 32.8% higher than its design value, whilst the other wall systems showed marginally lower U-values than their corresponding design Uvalues.

Assessing the Relationship between Measurement Length and Accuracy within Steady State Co-Heating Tests

“…The steady state co-heating method has largely been used within the UK, where it has been adopted in a number of building performance studies in the UK over the last two decades [8,[25][26][27][28][29][30] as well as recent tests exploring different wall structures [31], mobile home constructions [32] and a series of retrofit measures [33]. As the number of tests performed has increased, researchers have used these measured results to try and identify trends associated with this fabric performance gap [7], although higher sample sizes and wider ranges of buildings would both extend this analysis and add greater certainty to observed patterns.…”

Capturing Building Fabric Thermal Performance and Solar Heat Gains Through a Whole House Heat Loss Test – an In-Situ Study in Poland

“…The most simple methods of connecting the energy used for heating with the heat transfer through the building envelope with the use of the co-heating test excluded solar gains from the analyses [2,7,11].…”

“…where: E -daily average heat input [W], HTC -average heat transfer coefficient of the building's envelope [W/K], ΔT -daily average temperature difference between the interior and exterior [K]. Some researchers advised including solar gains in the calculation of the HLC factor, especially if the measurement were taken during days with periods of more intensive solar radiation [5,11]. The equation describing the energy balance was then complemented by the solar gains inside the building: Solar gains inside the building were modelled with the use of the TRNSYS simulation program, including external shading by the neighbouring building.…”

An experimental investigation into the comparative hygrothermal performance of wall panels incorporating wood fibre, mineral wool and hemp-lime

“…All panels used in the experiment have the identical design/calculated U-value of 0.15 W/m 2 K. Previously, tests were conducted in tests cells built of similar panels in a number of coheating tests as detailed in [40] that focused more on the overall energy use of the test buildings in steady state internal conditions. The current experiments use a large environmental chamber, installed in the Building Research Park, Wroughton, that allows wider range of controlled hygrothermal boundary conditions than those offered by coheating tests.…”