A solutions-based simulation approach to test the technical and economic feasibility of achieving low and zero carbon homes in the UK

Panel: Panel 7. Innovative buildings technologies

Authors:
Dr. Rajat Gupta, Reader, Oxford Brookes University, Department of Architecture,
Headington campus, Gipsy lane, United Kingdom
Smita Chandiwala, Researcher, Oxford Brookes University,
Department of Architecture, Headington campus, Gipsy lane, United Kingdom

Abstract

This paper describes the development, application and analysis of an interactive user-friendly Code for Sustainable Homes-based Sustainability Appraisal Toolkit (SAT). SAT runs on MS Excel and is used to evaluate the technical and economical feasibility of achieving Code levels 3, 4, 5 and 6 for a representative sample of new-build dwellings in UK for different scales of development (single-home, 25 homes and 250 homes). The scenarios are modelled using three standard housing types: detached house (104m ² ), mid-terraced house (79m ² ) and a low-rise flat (61m ² ).

A range of strategies are evaluated on both demand and supply sides of energy to meet different Code levels. The analysis reveals that if the fabric performance is improved, level 3 and 4 targets can be easily met with minimal low and zero carbon (LZC) technology for detached and mid-terrace houses. The study shows a considerable reduction in additional capital cost per dwelling (ACD) for LZC technologies to meet code level 4, which ranges from £4500 (Euro 4785) for a detached house to £2889 (Euro 3072) for 25 houses. To achieve level 5, ACD is estimated to be £26,000 (Euro 27,645) and £20,000 (Euro 21,265) for a detached and mid-terraced house respectively. Level 6 (zero-carbon) is the most prohibitive and ACD is predicted to be £46,500 (Euro 49,442) for a detached house and around £38,500 (Euro 40,936) for a mid-terraced home. Higher levels of cost savings can be expected for both levels 5 and 6 at community-level strategies. The research shows that it is difficult to achieve the required percentage improvement target in smaller, efficient dwellings such as flats due to the % reduction scale.

The research emphasises the importance of maximising energy efficiency improvements to the fabric and form of a dwelling, before adding low/zero carbon systems, and promotes a ‘low-energy first and then low-carbon' approach. Also, a mix of energy technologies is required depending upon the site and scale of development, and the cost varies with scale to meet different Code levels.