The London Plan goes Zero Carbon
You may not have been made aware of the changes to planning and building regulations in the Greater London area, several amendments to local planning rules now mean that new homes have to be built to Zero Emissions standards,
this means that many traditional construction methods no longer fit the bill, instead, move to better construction methods and the use of onsite renewable energy sources is fast becoming mandatory.
Working with one of our clients on a mid-sized project recently meant we had to find a solution or several solutions to complying with the new zero carbon requirement. Fortunately for us the client and architects had already specified a quality construction type, meaning that the project achieved its targets on U-Values and thermal bridges was an obstacle that had already been removed. The next step was to reduce the carbon impact for the development as a whole, being a block of apartments on a site limited in size and also being located in the heart of a town meant that some of the available renewable options were not feasible for the site, such as wind turbines, ground source heat pumps to name a few. With ample south facing roof space to install a solar POV array, this gave us an option to reduce the DER/TER for the site, given the quality of the construction the DFEE/TFEE complied with ease, now the problem was how to feasibly reduce the emissions to the zero carbon requiLooking
Looking into the available options further we managed to show that installing mechanical ventilation with heat recovery (MVHR) system and reduce the air permeability figure to 3, such a low air tightness figure is a minimum for using MVHR as the more air tight the construction the more effective the system, also SAP Calculation software is designed to require an air-tight construction to give the benefits of such a system. The next option we looked at was the glazing, double glazing was originally specified for the project, but improving them to triple glazing with a low U-value reduced the overall carbon emissions and the area weighted U-values, but we still weren't at zero, having looked at the feasibility of other renewable sources we realised that the solutions we had already implemented were about all we could do for the project, we had reduced the reduction in CO2 by an average of 68%, and were struggling to find the extra 32% to realise true zero carbon, after a bit of research we find that local authorities had a "Carbon Fund" this means that because of the difficulty in achieving zero carbon the developer could pay into a fund, which is designed to put money into off-site projects to reduce carbon dioxide elsewhere, this was the solution to the problem.
Carbon offsetting was always going to form part of the Governments drive to reduce carbon dioxide emissions from the built environment, as the clock ticked towards the 2016 deadline for zero carbon as part of the Code for Sustainable Homes the Government realised that it was never going to achieve what they set out to, so, they abandoned the Code for Sustainable Homes and decided to include some of the aspects of the Code into a more robust set of building regulations. Even then the idea would be to allow developers and house builders to offset their shortfall in CO2 reductions by either investing in offsite renewable energy schemes. Originally developers and house builders would have been able to trade "Carbon Credits" buying and selling CO2 by the tonne, but this marketplace never fully materialised. So the Carbon Fund was the next obvious solution.
Building Zero Carbon homes needs more than just a nod to CO2 reduction in construction, it needs education, showing developers how best to implement the requirements of Zero Carbon, as well as giving them examples of how this has been achieved by companies such as BRE, most traditional builders tend to stick to a time honoured construction process, but this is fast becoming ineffective as we move towards more energy efficient low carbon homes. The Government needs to help developers and house builders by showing them new construction methods, giving them information on available technologies and also putting forward a standard cost per tonne for the local authorities carbon funds, that way they could get a clear indication of not only the feasibility of building 21st century homes but the cost of failing to achieve true zero carbon.