New Build Performance Evaluation

Research undertaken by the Leeds Sustainability Institute (LSI) has been fundamental in establishing the concept of the 'performance gap' which is now ubiquitous in building energy efficiency policy. Our research has not only led to changes to Part L of the Building Regulations for England and Wales, but it has also established building performance evaluation (BPE) as a major focus for research council, government and industry funding.

One of the greatest impacts of the LSI research has been to provide empirical evidence that the party wall bypass could be responsible for a significant amount of heat loss and was contributing to the discrepancy between the predicted and measured heat loss of new dwellings, often termed the building fabric thermal ‘performance gap’. This work directly led to changes to Part L of the Building Regulations, and established cavity party wall insulation in UK domestic retrofit policy – potentially a multi-million-pound insulation market.

Below are case studies related to this research and access to all our research on behaviour change.

New build performance gap case studies

Implementing advanced energy standards for housing

Stamford Brook is a development of around 700 cavity masonry dwellings that was being constructed on part of the National Trust’s Dunham Massey Estate near Altrincham in Cheshire. Construction on the site commenced in 2004 and continued until around 2009/2010. The development was carried out under a partnership agreement between the land owner, the National Trust, and the two developers Redrow and Bryant Homes. The development partners were also participating in a 'Partners in Innovation' (PII) project with the Centre for the Built Environment at Leeds Metropolitan University that has investigated various aspects of the design and construction processes. The Stamford Brook PII project is a unique record of the achievements, successes, failures, problems and solutions that can occur during the implementation of an advanced energy standard on a large-scale housing development. Using participatory action research methodologies, the research project team has followed the progress of the development from initial discussions on the energy standard and environmental standard, through the detailed design process, observation of construction of the dwellings, performance testing of completed buildings and monitoring of occupied houses.

Research outputs

BPE of Prototype Low Carbon Dwellings

The Temple Avenue Project, funded by the Joseph Rowntree Housing Trust, outlines the initial evaluation of the design, construction and performance of two prototype low carbon dwellings and helps establish the extent to which an existing 1930s masonry house can be renovated so as to achieve a level of performance commensurate with the advanced energy and carbon standard of the prototype new dwellings. The two prototype dwellings contained some technological innovation and were constructed between July and December 2009. One prototype was constructed using thin-joint masonry construction and another using a structural insulated panel (SIPs) build system. The concurrent renovation works to an adjacent existing dwelling explored the impact of two standards of renovation, one reflecting the standard fabric measures that are currently considered to be cost effective and one reflecting the more challenging requirements of an 80% emissions reduction and incurring greater capital costs.

Research Outputs

BPE of sustainable housing development

This project set out to provide a robust approach to the evaluation and monitoring of the Elm Tree Mews sustainable housing development in York. The development is being undertaken by the Joseph Rowntree Housing Trust, supported by the Joseph Rowntree Foundation and is intended to address the issues involved in creating low carbon, sustainable housing. It is anticipated that the lessons learned will be fed back to the industry at large. The research project consisted of a retrospective evaluation of the design and construction process, performance measurements of the dwellings as constructed (compared with design expectations) and the monitoring of energy and other performance characteristics of the dwellings in use.

Research outputs

Nationwide BPE investigations into Low Carbon Homes

In 2011, the Technology Strategy Board (now Innovate UK) launched the £8million Building Performance Evaluation (BPE) Programme. An overarching aim of the BPE programme was to assemble comparable data and knowledge about a large number of buildings to enable analysis across the body of case study information, leading to generic findings conclusions and learning for the sector as a whole. As part of this Programme, the Centre for the Built Environment (CeBE) were successful in securing over £500,000 of external funding to undertake six post construction and early occupation studies (25% of all of the domestic projects awarded under the Technology Strategy Board BPE Programme) and two in-use performance and post occupancy evaluation studies. Additionally, all participants involved in the wider BPEP were required to adhere to standardised BPE practices based on the Leeds Beckett University Coheating Text Protocol.

Research outputs

  • Gentoo Passivhaus Racecourse Development, Sunderland
    Type of study – Post construction and early occupation.
  • Gentoo Passivhaus Racecourse Development
    Type of study – In-use performance and post occupancy evaluation.
  • Dormary Court, York
    Type of study – Post construction and early occupation.
  • Dormary Court, York
    Type of study – In-use performance and post occupancy evaluation.
  • Lancaster Cohousing Development, Lancaster
    Type of study – Post construction and early occupation.
  • Community in a Cube (CIAC), Riverside One, Middlesborough
    Type of study – Post construction and early occupation.
  • Derwenthorpe, York
    Type of study – Post construction and early occupation.
  • Lea Field Court, York
    Type of study – Post construction and early occupation.
  • Fletcher MJ; Johnston DK; Glew D; Parker J (2017), An empirical evaluation of temporal overheating in an assisted living Passivhaus dwelling in the UK. Building and Environment, 121, Pages 106-118
    https://doi.org/10.1016/j.buildenv.2017.05.024
  • JOHNSTON, D. and SIDDALL, M. (2016) The Building Fabric Thermal Performance of Passivhaus Dwellings—Does It Do What it Says on the Tin? Sustainability, 8(1), 97; DOI:10.3390/su8010097.
  • JOHNSTON, D. and STAFFORD, A. (2016) Estimating the Background Ventilation Rates in New-Build UK Dwellings – is n50/20 appropriate? Indoor and Built Environment. Published online before print January 28, 2016, DOI: 10.1177/1420326X15626234.
  • JOHNSTON, D. MILES-SHENTON, D.FARMER, D. and BROOKE-PEAT, M. (2015) Post Construction Thermal Testing: Some Recent Measurements. Engineering Sustainability. Volume 168, Issue 3, June 2015, pp. 131-139. DOI: 10.1680/ensu.14.00048.
  • JOHNSTON, D. MILES-SHENTON, D. and FARMER, D. (2015) Quantifying the Domestic Building Fabric ‘Performance Gap’. Building Services Engineering Research & Technology (BSER&T). Volume 36, No.5, September 2015, pp.614–627. DOI:10.1177/014362441557034.
  • JOHNSTON, D. FARMER, D. BROOKE-PEAT, M. and MILES-SHENTON, D. (2014) Bridging the Domestic Building Fabric Performance Gap. Building Research & Information. Volume 44, Issue 2, pp.147-159. DOI:10.1080/09613218.2014.979093.

Cavity party wall thermal bypass investigations

This work was funded by Eurisol, the UK Mineral Wool Manufacturers Association. This project followed on from the Stamford Brook field trial, which identified significant heat losses via party wall cavities in terraced and semi-detached masonry houses, and proposed various techniques to eliminate or minimise the effect. The purpose of this study was to extend the work carried out at Stamford Brook, and help in the development of practical low-cost solutions to mitigate of heat loss via party wall cavities.

Research outputs

Investigating the efficiency of ground source heat pumps

A collaborative 3-year research project funded by EPSRC in partnership with E.ON. The academic partners were: UCL (lead partners), Leeds Metropolitan University, Loughborough University, De Montford University, Kings College London, Cardiff University and the University of Greenwich. CCC uses the methodology of Action Research to engage users in the design of control systems which will reduce energy use (and therefore carbon emissions) in dwellings, whilst retaining or enhancing levels of comfort for the occupants. The aim was to achieve a 20% reduction in energy use through working more effectively with existing technologies and building fabrics, via the development of control systems which are both convenient to use and appropriate to the needs of users with a variety of lifestyles. The control systems were designed and tested in a way that complies with utilities’ CERT-2 obligations, and the project also developed design, installation and maintenance guidelines which will enable a wider application of important principles identified.

Research outputs

  • Production efficiency of hot water for domestic use, P.J.Boait D.Dixon D.Fan A.Stafford, Energy and Buildings 54, November 2012, Pages 160-168
  • Electrical Load Characteristics of Domestic Heat Pumps and Scope for Demand-Side Management. P. Boait and A. Stafford, Proceedings of CIRED 21st International Conference on Electricity Distribution. Frankfurt, June 2011.
  • Performance and Control of domestic ground-source heat pumps in retrofit installations. P.J. Boait, D. Fan and A. Stafford, Energy and Buildings 43 (2011) 1968–1976.
  • Long-term monitoring and performance of ground source heat pumps. A. Stafford: Buildings Research and Information, Vol 39, Issue 6, pp566-573, 2011.
  • Predicting In-situ Heat Pump Performance: An Investigation into a Single Ground-Source Heat Pump system in the context of 10 similar systems. A. Stafford and D. Lilley. Energy and Buildings
  • The Effects of Weather Conditions on Domestic Ground-Source Heat Pump Performance in the UK. A Stafford. Accepted for SEB12 International Conference, September 2012, Stockholm

Assessing the fabric thermal performance of holiday homes

The aim of this project was to undertake a number of in situ measurements of the thermal performance and airtightness of a small number of new 2016 model fleet hire holiday homes. The in situ measurements were undertaken to enable the heat loss attributable to each holiday home to be disaggregated into its constituent components. All of these measurements were undertaken for Bourne Leisure Limited, one of the largest holiday home park operators in the UK. These measurements were undertaken to enable Bourne Leisure Limited to determine the optimum levels of insulation (and U-values) that should be specified for the main external elements of their fleet hire holiday homes. This project presents the results obtained from undertaking detailed building fabric thermal performance tests on a small sample of new holiday homes. The results of these tests indicate that although a building fabric thermal performance ‘performance gap’ exists in all of the holiday homes tested, the results suggest that the ‘gap’ is much smaller than that documented for new build UK housing and may be more of a consequence of the way in which the design intent of these homes has been determined, i.e. a ‘prediction gap’, rather than a ‘performance gap’ between assumed and realised in situ performance. These results could be used by industry to develop more appropriate prediction tools that are relevant to holiday homes.

Research outputs

Assessing the airtightness of holiday homes

The aim of this project was to quantify the air permeability and identify the main areas of air leakage associated with a number of prototype holiday home hire fleet models that were being produced by Atlas Leisure Homes. It is estimated that in the UK, 200,000 residents live in park and holiday homes all year round, the majority of which are elderly and on low incomes. As these homes are often thermally inefficient and leaky, these residents are some of the most susceptible in society to fuel poverty. The results identified a number of common air leakage areas within the test caravans, suggesting that there may be a fundamental industry-wide issue associated with the way in which these homes are constructed which needs to be addressed. In addition, the results also indicate that utilising the air permeability metric within Sherman’s ratio (Q50/20) to approximate the average annual air infiltration rate, introduces a bias into holiday homes, due to their high surface to volume ratio. This bias is not unique to holiday homes and will be equally applicable to other building types with similar surface to volume ratios.

Research outputs

Low carbon homes; prototype testing

Hill Housing Ltd and Leeds Beckett University employed a Knowledge Transfer Partnership Associate to assist in the evaluation of prototype low energy homes in Cambridge. The associate, supported by Leeds Sustainability Staff undertook design reviews, building performance testing, in-use monitoring, post occupancy evaluation of the home and identified many successes and identified improvements that could be taken forward into the main multi-home scheme. The homes themselves outperformed all the homes the LSI have previously tested; the performance gap that was measured was within the margin of error of the test, meaning that this may be the first home built in the UK, that has been tested, without any measurable performance gap at all.

Research outputs

UK Passive House Conference, October 2019, Mainstreaming Passivhaus by 2030, Manchester, UK, - Chris Gorse speaker profile

Building performance evaluation for new build social housing

Wakefield District Housing (WDH) and Leeds Beckett University (LBU) were successful in securing funding for a Knowledge Transfer Partnership. The project focused on evaluating the performance of new build social sector housing.

The application of Dynamic Thermal Simulation models to WDH new build housing demonstrates the potential to evaluate a wide range of construction options at design stage. The DTS analysis work presented here also shows how calibration of models against measured and metered data can improve their accuracy and usefulness in considering alternative scenarios. The potential changes in construction and their impact on energy performance (and utility bills) has been quantified in this report. The DTS analysis also illustrates the potential risk of overheating in low-energy dwellings but also that this can be mitigated through simple design and operational changes, such as internal blinds or increased window opening angles.

As a whole, this in-use monitoring data demonstrates that the new build dwellings currently owned by WDH Ltd are relatively well performing. The in-use monitoring data does however also illustrate the wide range of user behaviour in the context of thermal comfort and also, some scope to offer advice to tenants on how small changes in behaviour may help them to reduce utility costs without adversely affecting their thermal comfort.

Contact the Leeds Sustainability Institute