Features | Buildings and Design

With some 26 million homes in the UK, including seven million social housing properties, the widespread introduction of low-carbon refurbishment techniques could see millions of tonnes wiped off the country’s carbon footprint each year and hundreds of pounds off the average home’s fuel bill.

In 2006, the UK Government launched the Code for Sustainable Homes to address carbon and energy issues. But this national standard for sustainable design and construction only applies to new homes, which represent less than 1% of our housing stock annually.
The main issue now is how can we make existing homes more carbon and energy efficient, whilst at the same time reducing home energy bills?

The ‘Value Carbon’ method

United House, a social housing contractor, has developed a low carbon refurbishment method that selects the best value improvements, giving the biggest cuts in household bills and carbon emissions for the lowest cost.

This method has demonstrated that significant changes can be made to carbon emissions by installing well chosen improvements in a home. Part of our challenge was to learn how to make these changes on a large scale so that housing providers could opt for these improvements as part of their existing Decent Homes programmes, which aim to improve the quality of social housing.

This groundbreaking new approach is being tested on a real home, which we call Green Living Islington by United House and Partners for Improvements Islington for the London Borough of Islington. The project is part of PFI Two, the UK’s largest housing refurbishment Public Financing Initiative (PFI), which provides financial support for public-private partnerships (PPPs). The Green Living home meets the Decent Homes standard and has energy saving technologies new to both London and to social housing.

The new initiative has been backed by the Sustainable Energy Academy, an organisation promoting education and action to reduce the carbon footprint of buildings and communities. SEA’s chairman John Doggart describes it as “the first time that sustainable practices have been combined with value engineering and the result is fantastic. It is a real exemplar in sustainable retrofitting.”

The basic principles underpinning the approach are three-fold: we use energy well by lowering demand, improving conversion efficiency of fuel to heat, fuel to light and fuel to appliances; we hang on to heat by improving insulation, draught proofing and glazing; and we obtain more energy from renewables.

Low-carbon refurbishment

When budgets are tight, one solution is to treat the refurbishment in two ‘fixes’. The cost of LCR versus the carbon saving for any home will look something like this:

 

In the 40 years to 2050, a property will probably have major repairs twice, so a pragmatic solution is to LCR cost-effectively the first time, then do the more expensive work (which often includes renewables) later. Renewables are in their infancy and they are expensive but they will become cheaper – maybe by as much as 50%. Today payback on renewables is poor but as energy becomes more expensive – and we can expect increases of 20% – their returns will improve.

The ‘first fix’ should include:

• Upgrading the heating with a condensing boiler, thermostatic radiator valves (TRVs) on all radiators, plus time and temperature controls;
• A hot water cylinder with foam lagging;
• Draught strip to improve AP; 
• Improving external wall and roof insulation;
• Low-energy lighting;
• Fitting used chimneys with closing doors to prevent room heat loss; and
• Adding enabling technology to simplify the ‘second fix’ renewables.

Green Living Islington

We selected a ground floor flat with solid walls and sash windows in a Victorian terrace for the Islington project. We set no pre-defined percentage carbon saving target or financial budget, but simply set out with the intention of doing the right thing for the lowest cost. We applied 24 improvements (but no renewables) and achieved a reduction in the carbon emissions from 3.8 to 1.1 tonnes per annum, using the Government's recommended method system, Standard Assessment Procedure (SAP). The decrease represents around a 70% reduction. Interestingly, had we only carried out these measures to the ‘tipping point’ (see graph above), the saving would have been around 50% – but for one third of the cost.

We have also developed the ‘Value Carbon’ assessment method to rate the effectiveness of each measure. SAP gives us the CO₂ saved by each and we estimated, then later confirmed, the cost of installing the measure, which allows us to calculate the ratio of the cost/kg CO₂ saved per annum for that measure. We then ranked the 24 measures from best to worst.

We included three innovative measures in the refurbishment: a newly developed ‘nano’ insulation material; a gas-fuelled boiler that generates both heat and electricity and even enables power generated to be sold back to the grid by the resident; and re-glazed sash windows with vacuum double glazing.

Ventilation loss is high in such properties and we undertook six separate AP tests that showed us exactly where the leaks occurred. Thermal images before and after refurbishment work demonstrated the overall improvement.

With the measures to achieve 70% carbon reduction installed, the saving on the utility bill was £1 per annum for every £64 of capital spend, and the carbon was saved at a cost of £8 per kg/per annum.If only the measures to give a 50% carbon reduction were deployed, the utility savings are improved to £1 for each £28 of capital spend, and a carbon saving cost £3.50 kg/per annum.

The Green Living home demonstrates that we can deliver good value low-carbon refurbishment as part of a Decent Homes programme. It also gives us the knowledge to carry out future work with residents in situ, and it highlighted the importance of engaging the resident with their newly refurbished home to obtain the greatest savings.

Conclusions

What is the future for wide scale low carbon refurbishment? It is vital that the UK gets a code for low carbon refurbishment of existing homes. Then the right choice of improvement measures will lead to good value refurbishment, which United House has demonstrated can be turned into a delivery process. Planning requirements must also be taken into account as these may well conflict with the best low carbon refurbishment choices. Budgetary restrictions mean we have to be realistic about the level of carbon saving, while a 70% carbon saving in the Green Living home is desirable, costs are several times higher than for a 50% carbon saving. Deep carbon cuts to all existing homes are unaffordable now but improvements to an intermediate level are attainable. When the renewables industry has evolved, the time will come for more extreme measures.

Alistair Sivill

For further information:
www.unitedhouse.net/
www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/codesustainable/
www.communities.gov.uk/housing/decenthomes/
www.sustainable-energyacademy.org.uk/

Author bio
Alistair Sivill is Technical Director of United House, one of the UK’s foremost specialist housing and construction companies with more than 40 projects underway across London and the South East. Alistair, who has a degree in Mechanical Engineering and a PhD, has been with the Group for 25 years, starting and running the Alpha Boiler Company within the United House Group. He is now concentrating on developing new products and processes to keep United House at the forefront of Low Carbon Refurbishment.