How to cost-effectively retrofit existing housing stock

Retrofitting existing housing gives better energy and carbon savings per pound spent than any new build measure or renewable technology. Key energy saving retrofit measures to consider are:

• controlling ventilation by draught proofing, blocking up unused chimneys, sealing leaky timber ground floors and introducing humidity controlled extractor fans where needed;
• insulating solid walls, replacing single glazed windows with new high performance double glazed windows, filling cavity walls, and insulating lofts and roofs;
• installing new highly efficient gas condensing boilers with thermostats and programmers and thermostatic radiator valves.

But this is just the technology. A good retrofit will look at much more than the physical changes to an individual house. Here are five points to bear in mind.

1. Think about the wider effects of each measure

Retrofitting measures, as above, should be considered as a package. That will mean maximum energy savings but will also avoid adverse effects such as increasing dampness and mould by excessively reducing ventilation or creating cold bridges (areas that are especially cold, as partial insulation of some areas can result in others becoming colder than before).

2. Look at the bigger picture

Arup’s experience suggests that the greatest efficiencies can be made by taking a wider approach to refurbishment. Those embarking on a refurbishment scheme should focus on the desired overall outcome. Some of the worst housing in energy terms is also occupied by the poorest people, both low income renters and homeowners.
Carbon reduction is king at the moment, but it is also worth considering how the retrofit might affect factors such as individual and community well-being, water use, climate change adaptation and food provision.

3. Consider an area-wide strategy

Arup is carrying out a study in Bristol with developer Rok and sustainable development body Forum for the Future, looking at the business case for carrying out retrofit schemes on a large scale. Early results suggest that you can make greater financial savings (and equivalent carbon savings) by retrofitting a ‘cluster’ of homes.

4. Tailor the strategy to different housing types

There is no ‘one-size-fits-all’ approach to existing homes. For example, the Bristol study identified 237 different housing types in the city region. Even within one housing type, there may be other differences in terms of the planning consent that will be required.

5. Take a whole-house approach

This can result in cost savings as the trades can work together to ensure works are undertaken in the most logical order. Using multi-skilled professionals can also create cost savings, for example one tradesperson may be able to install both wall and loft insulation.
The task of addressing existing building stock may seem daunting, but the cost of doing nothing is likely to far outweigh that of change or the penalty for regulatory non-compliance. The positive effects of upgrading existing building stock will benefit users, communities and the environment.

Ann Cousins is a sustainability consultant at Arup

Have your say

You must sign in to make a comment