Anne Stafford, David Johnston, Dominic Miles-Shenton, David Farmer, Matthew Brooke-Peat and Chris Gorse
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…
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. The paper aims to discuss these issues.
Design/methodology/approach
Leeds Metropolitan University has more than 20 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 coheating 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 to 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.
Details
Keywords
Rajat Gupta, Matthew Gregg and Rohini Cherian
The field of building performance evaluation (BPE) forms a fragmented whole with tools and methods that are not widely applicable. In response, the purpose of this paper is to…
Abstract
Purpose
The field of building performance evaluation (BPE) forms a fragmented whole with tools and methods that are not widely applicable. In response, the purpose of this paper is to develop and demonstrate a novel BPE framework to bring consistency and flexibility in evaluating actual building performance.
Design/methodology/approach
The paper critically reviews and evaluates existing BPE methods and techniques and situates them in different building life stages. Using a hierarchical approach, a “BPE framework” is devised for new and existing buildings as well as refurbishments. The working of the BPE framework is demonstrated by applying it to four discreet BPE studies to enable cross-comparison of different BPE approaches based on their stage of application, depth and duration of BPE investigations.
Findings
The framework is designed to have four graduated levels starting at the “basic” level and developing incrementally to “core”, “comprehensive” and “advanced” levels, thereby focussing on “need to know” rather than “nice to have”. The framework also offers a mechanism to map different types of BPE studies with varying scope and content.
Practical implications
As we enter a world of smart meters and smart buildings, we are transitioning into a new future of understanding building performance. The study helps to better understand which BPE method can be used to study what aspect of building performance and in what building lifecycle stage, against time, cost and user expertise.
Originality/value
The graduated and flexible framework helps to bring consistency in evaluating building performance in an otherwise fragmented field, to help improve building performance.
Details
Keywords
Matthew Li, David Allinson and Kevin Lomas
The purpose of this paper is to identify the impact of traditionally unmonitored energy sources and sinks on assessment of the as-built thermal performance of occupied homes. The…
Abstract
Purpose
The purpose of this paper is to identify the impact of traditionally unmonitored energy sources and sinks on assessment of the as-built thermal performance of occupied homes. The analysis aims to demonstrate the potential scale of uncertainties introduced in a heat balance estimation of the heat transfer coefficient (HTC) when using in-use monitored data.
Design/methodology/approach
Energy flows for two UK homes – one a 1930s dwelling with high heat loss, the second a higher-performing 2014-built home – are predicted using the UK Government’s standard assessment procedure (SAP) and visualised using Sankey diagrams. Selected modelled energy flows are used as inputs in a quasi-steady state heat balance to calculate in-use HTCs as if from measured data sets gathered in occupied homes. The estimated in-use HTCs are compared against SAP-calculated values to illustrate the impact of including or omitting various heat sources and sinks.
Findings
The results demonstrate that for dwellings with low heat loss, the increased proportion of heating demand met by unmetered internal and solar gains informs a greater sensitivity of a heat balance estimation of the HTC to their omission. While simple quasi-steady state heat balance methods may be appropriate for dwellings with very high heat loss, alternative approaches are likely to be required for those with lower heat loss.
Originality/value
A need to understand the impacts of unmetered heat flows on the accuracy with which a building’s thermal performance may be inferred from in-use monitored data is identified: this paper illustrates the scale of these impacts for two homes at opposite ends of the energy performance scale.