Mar 30, 2021

Over and above costs of tighter standards in new builds

The Committee on Climate Change (CCC) published an “over and above” cost for energy efficient new build of £4,800 [1]. However, many building professionals we speak to cannot replicate this figure when they are planning an EPC A new build. We took a closer look at the figure.

The CCC document references a study by Currie and Brown, in combination with AECOM [2], which examined the cost impacts of reducing space heating demand, alongside low-carbon heat uptake in a variety of domestic and non-domestic scenarios. The study examined different sources of low-carbon space heating and water including an Air Source Heat Pump (ASHP) and Low-carbon Heat Network (LCHN) against a traditional gas boiler.

For a semi-detached new build, built in 2020, the calculated additional capital costs of reducing the space heating demand to 15 kWh/m2/yr in combination with the use of an ASHP was estimated to be £4,800; this is relative to building a home to current standards with a gas boiler. A 3.9% increase on build cost is documented. The costing is reflective of typical national costs, of a medium housebuilder using traditional construction methods, using a reasonably efficient supply chain, design development, and construction process. However, the build cost is sensitive to a range of design and specification variables, economies of scale and regional variations and should be taken as indicative only.

So, how have they come to this?

15 kWh/m2/yr represents an ultra-high energy efficient building and have considered the packages of improvement measures that would be taken to meet the space heating demand including the walls, u-values of doors, ventilation, air permeability.
The additional cost is divided into individual improvements in ventilation, air tightness, glazing and fabric cost.
The future improvement in the systems efficiency has been incorporated into the models to recognise the ongoing refinement of technologies in new build.
The distribution of the heat within the home has been considered. In a very energy efficient home, there is a low heating demand. The heating distribution pipework will be shorter and have a reduced number of radiators. A suggested 75% reduction in the cost of radiators and pipework can be expected in a home of 15 kWh/m2/yr.

The researchers used their own internal costing data within this study. However, ASHP installation is considered a cost-effective solution to low-carbon heat supply in new builds from 2021. The relative cost of these tighter standards and adopting a low-carbon heat network is expected to reduce over time.