In the UK, it is recognised that there is often a discrepancy between the measured fabric thermal performance of dwellings as-built and the predicted performance of the same dwellings and that the magnitude of this difference in performance can be quite large. This paper presents the results of a number of in-depth building fabric thermal performance tests that were undertaken on three case study dwellings located on two separate Passivhaus developments in the UK; one masonry cavity and the other two timber-frame. The results from the tests revealed that all of the case study dwellings tested performed very close to that predicted. This is in contrast with other work that has been undertaken regarding the performance of the building fabric, which indicates that a very wide range of performance exists in new build dwellings in the UK, and that the difference between the measured and predicted fabric performance can be greater than 100%. Despite the small nonrandom size of the sample, the results suggest that careful design coupled with the implementation of appropriate quality control systems, such as those required to attain Passivhaus Certification, may be conducive to delivering dwellings that begin to 'bridge the gap' between measured and predicted fabric performance. KeywordsAir tightness, building performance, housing, thermal barrier, coheating, heat flux. ContextOver a number of years, it has become evident that there is often a discrepancy between the predicted energy and thermal performance of a building and the measured performance of that building in-use. This discrepancy is often referred to as the 'performance gap'. The 'performance gap' affects domestic and non-domestic revealed discrepancies between the measured and predicted energy and thermal performance of whole buildings, or individual building elements. The reasons identified for the discrepancies in performance tend to be widespread and highly context specific. Despite this, they can be broadly categorised into three main areasthose relating to the thermal performance of the building fabric, those relating to the energy performance of the building services and those relating to occupancy. It is also important to recognise that all three of these areas are also influenced by the external environmental conditions. This paper is concerned with the thermal performance of the building fabric in new UK dwellings only. Despite this, the findings from this paper are likely to be equally applicable to other building types both within the UK and abroad. 2

To meet targets on fuel poverty, energy efficiency and carbon emissions existing homes need to be more energy efficient. We report the results of a participatory action research project to explore the challenges associated with energy efficiency retrofit programmes and ways to better implement future schemes.Six focus groups were held with 48 participants from a range of energy efficiency roles. Data were analysed thematically using the research question "What are the challenges presented by implementing energy efficiency retrofit programmes".We identified four themes in the data: Funding mechanisms; Predicting performance; Installation; and People. Challenges include funding mechanisms for retrofit programmes resulting in insufficient time to plan, publicise, implement and evaluate a scheme and insufficient flexibility to specify the most appropriate intervention for individual homes. Site workers sometimes need to adapt retrofit designs because of insufficient detail from the designer and can equate quality of installation with quality of finish. Landlords and occupier behaviour can impact on the programme's success and there is a need for greater information on benefits for landlords and for energy behaviour change interventions run alongside retrofit programmes for occupiers. There is a need for outcome evaluations of retrofit schemes with the results shared with stakeholders.

No 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.

In the UK, it has become apparent in recent years that there is often a discrepancy between the steady state predicted and the measured in situ thermal performance of the building fabric, with the measured in situ performance being greater than that which has been predicted. This discrepancy or 'gap' in the thermal performance of the building fabric is commonly referred to as the building fabric 'performance gap'. This paper presents the results and key messages that have been obtained from undertaking a whole building heat loss test, a coheating test, on seven new build dwellings as part of the Technology Strategy Board's Building Performance Evaluation Programme. While the total number of dwellings involved in the work reported here is small, the results illustrate that a wide range of discrepancies in thermal performance was measured for the tested dwellings. Despite this, the results also indicate that it is possible to construct dwellings where the building fabric performs thermally more or less as predicted, thus effectively bridging the traditional building fabric 'performance gap' that exists in mainstream housing in the UK. Keywords chosen from ICE Publishing listEnergy; field testing & monitoring; thermal effects. List of notation ∆Tis the difference between the mean internal and external air temperature.

No abstract

No abstract

No abstract