Refurbishment verses new build
How does 89 Culford Road compare to a new house? The current benchmarking system for new homes is the Code for Sustainable Homes. However, it is important to note that this system can only assess new dwellings. At present the only (BRE-backed) assessment tool that can be used for refurbished homes is Ecohomes, although this hasn't been updated since 2006. BRE is in the process of developing a domestic refurbishment assessment scheme, but this is not yet available.
Looking at the Code for Sustainable Homes and making small adjustments (not possible in a real assessment), the house would achieve a rating of Level 4. While a lot of the Code looks at the periphery of the construction process, the key elements of a rating are the energy and water categories. These have mandatory levels to reach to receive a rating at a particular level.
The 80 per cent reduction of energy use at 89 Culford Road has helped score highly here, but to reach the Level 5 rating a 100 per cent improvement would be needed, and even more for Level 6. The water issue would also pass the requirements of the higher levels of the Code because of the rainwater harvesting strategy.
The AECB Carbonlite silver and gold standards were also used, with the house falling in between the two levels. These standards use the German PHPP software to calculate energy usage as it is more capable of predicting energy use accurately in low energy buildings compared to the current version of SAP.
Leaving aside the assessment methods (which are only tools of prediction), 89 Culford Road will be monitored to provide a real measure of performance. Its lessons can then be rolled out across the domestic sector, with hopefully the anticipated energy savings achieved in practice. The first set of monitoring equipment has been installed by the insulation manufacturer Knauf.
Sensors have been installed into the walls, particularly on the front wall, and at the interface between different materials to give a temperature gradient through the wall. This should provide an evidence base and allow Knauf to make recommendations as to how its product could be better used. The house could also be the subject of MSc theses.
What 89 Culford Road illustrates is the sheer degree to which the UK's existing domestic housing stock must be improved if the country is to have any chance of meeting its carbon targets. The effective refurbishment of our existing housing stock is non-negotiable. It's a standard that must apply to all domestic dwellings, not just the small fraction of new homes that will be built - probably sporadically given normal economic cycles of growth and recession - between now and the next 40 years.