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Low carbon - how to prepare for the Part L building regs

Better business: building regulations, contract law, gas safety

The introduction of the new Part L Building Regulations in October means we are going to have to reduce new building emissions by an average of 25 per cent.

Looking at the way that the new targets have been generated, the actual emission reduction will depend on the building type.  Buildings that have significant

emissions from domestic hot water, such as hotels and sports centres, may only have to reduce emissions by 15 per cent, while shallow plan, air-conditioned offices

may have to reduce them by as much as 40 per cent. This will equalise the cost of implementing the new regulations across building types.

 

Energy consumption

It’s now recognised that with the significant increases in the current and future cost of energy, we must look to reduce energy consumption as well as emissions.

The methodology has attempted to address this by reducing the target emissions for biomass heating solutions to ensure fabric efficiency is addressed by designers.

By testing an example building we have found that with a biomass boiler, a building will emit almost 18 per cent fewer emissions; with heat pumps the figure is 3 per cent fewer, while direct electric heating cuts emissions by 10 per cent more than that gas.

This means the emissions reduction could range between 14 and 45 per cent and it will be interesting to see how this will influence the choice of heating systems in new buildings.

EPC fan emissions are also a major contributor and therefore the choice of mechanical ventilation system is critical.  Where all air constant volume systems are provided, fan emissions are up to two and a half times higher than if a fan coil were to be used. This has resulted in a move towards more passive solutions, such as chilled ceilingsand beams.

As there is a new, more realistic method for calculating fan energy consumption, we have reviewed the effect of using a constant volume system and found it is now only 1.6 times higher that of a fan coil unit system. Again, it will be interesting to see what effect this will have on our designs.

 

New methodology

One of the principles of the EPC is that a prospective building owner or tenant can compare the carbon dioxide emissions of buildings.

Although the methodology for the reference building, from which the benchmark is taken, has not changed, the methodology used to calculate the emissions from the actual building has.  That, together with the significant increase in the electrical emission factor for electricity, means that an EPC calculated for a building with the current methodology will not be the same as that calculated with the new methodology.

Therefore, BREEAM ratings for building designs that are being assessed now and will be completed after October 2010 have the potential to lose Ene1 credits.  We will therefore be ensuring that there is sufficient margin in any BREEAM assessment so that the goal of achieving BREEAM ‘outstanding’ or ‘excellent’ is not

compromised. Let us hope that the issue is not further complicated by a change to the Ene1 credit scale.

We welcome the emphasis on energy consumption, as well as emissions reduction, with what we hope will be a more equitable additional cost so that we can deliver

designs that reduce the use of energy and whole life cost of our buildings.

 

David Kingstone is an associate at Buro Happold