m&e sustainability

30 per cent of the country’s total CO2 emissions come from homes, but the Government wants us to build 220,000 new ones every year while simultaneously reducing environmental impact. It is hard to see how this equation is going to balance, but the politicians think they have a trump card: the Code for Sustainable Homes.

On January 1 this year, Level 3 of the code became mandatory for Housing Association properties and projects funded by English Partnership. In 2010 it becomes mandatory for all new homes as part of the new Building Regulations, and in 2013 the standard will rise to Level 4 finally reaching Level 6 or ‘zero carbon’ in 2016.

The Code becomes, in effect, a licence to trade for housebuilders giving this particular piece of legislation enormous significance.

There are nine categories within the Code and some are more important than others in terms of the number of points they score towards the overall level. Energy is the most significant element counting for 36.5 points (out of a possible total of 104) – more than a third of the entire Code. As well as being the most important element, it is also, happily, the one our industry has most influence over.

Other design aspects include water conservation and run-off, materials used, health and well-being of occupants, waste, and pollution. The intention being that new homes should be more sustainable in the widest sense as they will be easier to maintain and cheaper to run in the long-term.

To reach Level 6, builders must score 90 out of 100 points by combining a variety of measures. Some of the categories are mandatory while the rest are tradable. A property is assessed both before and after construction to make sure the design is not compromised or corners cut.

Accredited inspectors will carry out the assessments and they will apply a Dwelling Emissions Rate (DER) to calculate a home’s carbon footprint. This measures kilogrammes of CO2 per square metre per year and is a step up from the current Target Emissions Rate (TER), which is part of the 2006 Building Regulations.
The inspectors will use the SAP 2005 method to calculate improvements and a 25 per cent improvement on current regulations will secure Level 3, but a 44 per cent jump is required for Level 4 and a 100 per cent improvement will be needed to get to Level 6 by 2016.

Better insulation, fitting condensing boilers and improving controls can get us pretty close to Level 3, but as we build up towards Level 6 we will need to increase our design ideas to look at more complex issues like maximising solar gain by correctly orientating the building as well as cutting out thermal bridging and using more renewables.

Many local authorities are already pushing for renewables as part of the planning process  with many developers now obliged to deliver at least 10 per cent of the property’s needs from renewable sources. Level 4 of the Code calls for a minimal amount of renewables and Level 6 will only be achieved with significant amounts of renewables and other off-grid energy solutions.

As insulation levels increase, there will be a growing need for more ventilation to deal with high levels of CO2 and condensation. Heating engineers can play a key role in the wider deployment of mechanical ventilation systems with heat recovery to meet this need. Many of these systems, if properly designed and installed, can both reduce air changes while also improving indoor air quality at up to 95 per cent energy efficiency.

The future will see homes being built with smaller rooms, better insulation and lower heat losses so leading to lower output boilers, more mechanical ventilation and renewables coming in to replace conventional systems. Another big aspect will be reduction in water usage, which will lead to smaller DHW storage, reduced flows through boilers with an even greater proportion of hot water generated from renewables – particularly solar.

At the moment, our market is dominated by the gas central heating boiler, but in the future no single technology will dominate as house builders look for a mixture of solutions to help them meet the increasingly stringent requirements of the Code.

We will also have to be mindful of our impact on pollution by carefully monitoring the type of materials used in our systems. Also, NOx emissions will be carefully scrutinised with levels restricted to below 40mg per kWh.
Homes will have to have smaller footprints to minimise their ecological impact. They will get smaller and taller to meet emissions targets and all this has a significant impact on the design of heating systems.

Smaller output boilers, perhaps linked to underfloor heating, and much smaller – or even non-existent – hot water storage linked to solar collectors will be deployed alongside on-site microgeneration technologies like Combined Heat and Power (CHP). This will radically change the way we approach our projects and will postion our profession at the forefront of future house building plans.

*Billy Wilgar is a member of the HVCA’s Heating and Plumbing Services (HAPS) Group.

www.hvca.org.uk