Cracking the product Code for Sustainble Homes

Launched in December 2006 by the Department for Communities and Local Government, the Code for Sustainable Homes comes into effect in April 2007. For the public sector, all Government-funded housing schemes through English Partnerships and the Housing Corporation will have an obligation to follow the Code. In turn, as private sector housing developments are now required to include a proportion of social housing, the Code is also set to be adopted by the private sector in an advisory capacity.

So what do specifiers and architects need to look out for with the arrival of this legislation, and how can they ensure they use the best materials to meet the challenges ahead to 'Crack The Code'? The fundamental mission statement of the Code is to 'encourage developers to offer more innovative solutions to home building, whilst empowering homebuyer', and is one of a package of measures launched by the Government to promote zero carbon developments. The Code has been introduced to act as a driver for best practice in building sustainable homes, and will become the single national standard for home designers and builders in development projects, whilst at the same time assisting homebuyers in their choice of home.

From a technical perspective, the mechanics of the Code are essentially based around assessment and performance measurement using the BRE EcoHomes scheme. The Code uses a system based on a points scheme that classifies a property according to its sustainability criteria - indicated by 'stars'. A home can achieve a sustainability rating from one (*) to six (******) stars depending on the extent to which it has achieved Code standards. One star is the entry level - above the level of the Building Regulations, and six stars is the highest level - reflecting excellence in sustainability terms. It is anticipated that most housing associations will adopt Code rating three as a minimum standard.

This ratings system is similar to that currently used for the energy rating of white goods, giving customers a simple way to compare the sustainability credentials of new homes for sale or rent. The Code covers standards of performance in the following nine categories that cover the building envelope as well as essential services: Energy; Water; Materials; Surface water run-off; Waste; Pollution; Health & well-being; Management and Ecology. Buildings are allocated points against each of these criteria, which add up to the total star-based ratings score.

To achieve a Code rating of three, a total of 57 points are required. Energy efficiency and water efficiency categories also have minimum standards that must be achieved at every level of the Code, (5.8 points for energy and 4.5 points respectively), recognising their importance to the sustainability of any home. Apart from these minimum requirements, the Code is completely flexible. Developers can choose which and how many standards they implement to obtain 'points' in order to achieve a higher sustainability star rating. Four of these categories are of particular importance when considering specification of concrete building products and methods of construction - energy; materials; pollution and health and wellbeing. Take energy and carbon dioxide emissions as the first example. To achieve the 5.8-point rating required for energy conservation, a building has to achieve a 25% reduction in its carbon dioxide emissions ratings better than Building Regulations Part L 2006.

To meet this minimum energy requirement, building products used in the construction process need to offer high levels of thermal efficiency. It is here that concrete products, such as the blocks supplied by Tarmac Topblock, can play an important role. The high thermal mass properties of concrete, combined with the adaptability of blocks, mean that walls can be constructed in conjunction with bricks, insulation or renders to offer U-values of less than 0.30W/m²K. Add to this the fact that homes build with concrete products can emit up to 15 tonnes less carbon dioxide over the lifetime of a building compared to timber frame construction.

Not only does building with concrete blocks help to meet energy and carbon dioxide emission requirements, it also enables companies to gain additional Code points from the materials category, where up to 4.5 additional points are available. Information about the ratings for Tarmac Topblock products and different block-based construction methods can be found by referring to BRE's Green Guide to Housing Specification (GGHS). This Guide acts as an indication as to the number of Code points that particular block products or block-based construction methods will merit. As with Part L, which was revised in 2006, the GGHS is set to be revised later this year. These revisions to GGHS will be extremely important for specifiers to help them meet the ongoing requirements of the Code. At Tarmac, we will be updating our technical information to reflect any relevant changes to GGHS, which will enable customers to be clear as to the environmental status of our block products and their associated Code rating.

By also taking into account responsible sourcing of materials - which can earn up to 3.6 extra points - specifiers should consider exactly where the raw materials used in the construction of building products come from. Here, dealing with responsible suppliers that can prove traceability through quality manufacturing processes will ensure a greater number of points are secured. Unlike other structural building materials like timber - where it's estimated that up to 44% of imported supply is thought to be from illegal logging or poorly managed forests - Tarmac Topblock products benefit from a transparent manufacturing process and local availability of raw materials, with over 95% sourced from the UK. Continuing on the points trail, the next important category for blocks is pollution. Focusing on the cradle-to-grave manufacturing and construction process, the Code's pollution section centres on the use of substances that have global warming potential (GWP). Since no substances of GWP are used within Tarmac Topblock'’s products and processes, our blocks can be used in conjunction with other GWP-free products in the construction process, to achieve maximum points for minimising pollution.

Perhaps one of the most relevant categories for block construction is the health and well-being section of the Code. This relates to factors such as the overall acoustic performance of a building. Due to its high density, concrete block products - when used in the construction of partition walls - are able to exceed standards of sound insulation as specified under Part E Building Regulations. Depending upon the level of pre-completion testing undertaken and the commitment to achieve specified levels of acoustic performance, up to 4 points can be awarded for block products in this section.

In conclusion, more than 30 per cent of the points required to reach a three-star Code rating can be achieved using concrete blocks in conjunction with other associated products. So for companies wanting to attain the maximum rating, it is important to consider blocks when specifying products for the construction of the new homes. With continuing updates to Building Regulations and the Code for Sustainable Homes, house builders can sometimes be faced with a bewildering array of challenging targets and new product combinations offering different point potentials. Therefore, it is vitally important that companies take advantage of the free technical expertise and advice offered by manufacturers like Tarmac Topblock before selecting products for their building project.