Adding value and meaning to coheating tests

Abstract

Structured Abstract:Purpose: The coheating test is the standard method of measuring the heat loss coefficient of a building, but to be useful the test requires careful and thoughtful execution. Testing should take place in the context of additional investigations in order to achieve a good understanding of the building and a qualitative and (if possible) quantitative understanding of the reasons for any performance shortfall.Design/Methodology/Approach: The authors have access to more than twenty years of experience in coheating testing. This experience is drawn upon to discuss practical factors which can affect the outcome, together with supporting tests and investigations which are often necessary in order to fully understand the results. Findings:If testing is approached using co-heating as part of a suite of investigations, a much deeper understanding of the test building results. In some cases it is possible to identify and quantify the contributions of different factors which result in an overall performance shortfall. Practical implications:Although it is not practicable use a fully investigative approach for large-scale routine quality assurance, it is extremely useful for purposes such as validating other testing procedures, in-depth study of prototypes or detailed investigations where problems are known to exist. Social implications:Successful building performance testing is a vital tool to achieve energy saving targets.Originality/Value: The approach discussed clarifies some of the technical pitfalls which may be encountered in the execution of coheating tests and points to ways in which the maximum value can be extracted from the test period, leading to a meaningful analysis of the building's overall thermal performance.

First evidence for the reliability of building co-heating tests

“…In the quasi-steadystate tests, the amount of energy required to maintain a constant, raised, indoor temperature is measured, and the total heat-transfer rate is inferred by a simple energy balance. The most prevalent example of this method is the co-heating test, which has been in existence since the early 1980s (Everett, 1985;Siviour, 1981), but has been more widely used in the last 10 years in both the UK (Alexander & Jenkins, 2015;Guerra-Santin, Tweed, Jenkins, & Jiang, 2013;Jack, 2015;Jack, Loveday, Allinson, & Lomas, 2015;Johnston et al, 2016;Lowe, Wingfield, Bell, & Bell, 2007;Stafford et al, 2014;Stamp, 2015;Stamp, Lowe, & AltamiranoMedina, 2013;White, 2014) and the rest of Europe (Bauwens & Roels, 2014;Bauwens, Standaert, Decluve, & Roels, 2012;Meulenaer, Veken, Verbeek, & Hens, 2005). The co-heating test is the most commonly and widely used test of whole-building thermal performance at the time of writing.…”

Measuring and modelling retrofit fabric performance in solid wall conjoined dwellings

“…Although the coheating test in isolation cannot explain reasons for gaps in performance, it does provide an opportunity to carry out additional fabric tests, such as heat flux measurement and air pressurization, which can provide information to identify areas of poor performance [48].…”

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

“…Evidences suggest that there is a discrepancy between the predicted and actual energy use in the buildings [5] , the mismatch is broadly referred to as the 'energy performance gap' [6]. The 'energy performance gap' between the actual energy use and the calculated energy use of buildings is subject to scores of academic discussions [5][6][7][8][9][10][11][12][13]. Sometimes the amount of discrepancy is reported as 100% or more [5], e.g., Erhorn [12] reported a performance gap of 300%.…”

“…The 'energy performance gap' between the actual energy use and the calculated energy use of buildings is subject to scores of academic discussions [5][6][7][8][9][10][11][12][13]. Sometimes the amount of discrepancy is reported as 100% or more [5], e.g., Erhorn [12] reported a performance gap of 300%. The reasons for this 'energy performance gap' is widely attributed to poor prediction of actual energy use (design stage), poor quality of construction, poor service design, discrepancy between design specification and the specification of the construction as-built (construction stage) and user behaviour and 'Rebound Effect' (operational stage) [8,9].…”