Green is good

The winter of 2010 saw Approved Document L (Part L) amended in order to help the UK meet its carbon reduction targets for new buildings. The amended Part L will  not only help the Government meet its strict targets, but will also prove beneficial for businesses as it will result in a reduction of overall energy costs in the long run.

While the new Part L guidelines have been well publicised, many businesses are finding it difficult to know what steps to take in order to comply. One danger many companies face to is spend significant amounts of money on products and not see a return on their investment.

Renewable energy and sustainable products have grown in popularity over the past five years, and there are some incredibly efficient and sophisticated products on the market. The tricky bit is determining which options are the most appropriate for the building project being undertaken.

The designers need to submit iSBEM calculations at design/conceptual stages and after completion. Some principle aspects include actual i.e. elemental U-values such as the: roof, rooflights, walls, floors, windows and doors. However, other critical aspects, such as thermal bridging and air leakage are initially based on assumptions by technical staff.  

In the UK, Building Regulations state the ultimate objective is to reduce CO2 emissions across all buildings; domestic, non-domestic and refurbishment of existing buildings. This energy efficiency aim has culminated in Approved Document L (conservation of fuel and power), which is the regulation’s technical guidance that England and Wales must work towards; for Scotland it will be known differently as Technical Standard Section 6.

The primary focus for England and Wales is newly built, domestic buildings. The amendments stipulate an “aggregate 25 percent” improvement across all non-domestic buildings is required.

CA Group realised that businesses were confused regarding which products would offer them greatest efficiency.  Expensive options don’t always provide the best outcome and companies find a lack of return on investment become massively obvious, very quickly. Many clients also haven’t realised that small, inexpensive methods could be incorporated into the design which could have a greater impact on cost savings that some of their more expensive counterparts.

Recent developments in the accreditation of renewable products such as Transpired Solar Collectors have helped publicise their efficiency and value. For the first time in the UK, they have been officially recognised as a renewable technology having been incorporated into the SBEM computer programme.

SBEM4 is a tool that helps architects and mechanical engineers design greener buildings. With its proven heating cost reductions of up to 50 percent, one Transpired Solar Collector on offer is the SolarWall® system, which easily exceeds the Merton Rule requirement for renewable energy, while also offering the usual paybacks through energy savings of as little as three years for new build and seven years for refurbishment projects. It is a combination of these features that not only helps companies comply to Part L, but also provides a guaranteed return on prior investment.

CA Group’s experience in the field of sustainable building helped us to understand that many businesses would benefit from a tool that put into real terms the effect that certain products would have on U-values and a building’s efficiency.

Accompanying the approved document is the 2010 National Calculation Methodology, which outlines how the 2010 notional building is defined in terms of elemental U-values, air permeability etc, with the following values.

The new method of compliance, would suggest utilising the notional building U-values, the reality is that this is not the case, as proof of compliance is via a full iSBEM calculation which includes the services; lighting and heating.

Also the table does not take account of the effects of solar gain, which must be considered when measuring  building calculations.  

While there are no significant amendments to the building envelope performances, in terms of implications to manufacturers and installers, enhancing thermal performance beyond the values stated above, would incur costs associated with primary and secondary steelwork, prelims, construction programs, plant hire, etc., would all increase to accommodate larger, heavier sections/thicknesses.

This lead CA Group to develop the creation of the Building Envelop Calculator; a web-based tool available freely to specifiers and developers. It allows users to enter details for a proposed non-domestic building whether it is a school, warehouse, hotel or any other type of non-domestic building, and alter elements such as U-values and air permeability to see the effect on achieving a pass or fail.

CA Group knows that a good building envelope design is critical to creating a building that meets the ever more challenging Part L requirements and hopes this tool will help identify what goals can ultimately be achieved.

The tool has already been piloted by a number of architects including Martin Herron, head of sustainability and knowledge management, RPS Group, Newark. He believes: “It is a useful tool in helping to evaluate the options to improve the thermal performance of the building envelope”.

The recent changes can be daunting but by utilising the Building Envelope Calculator designers could benefit from viewing the expected results without the cost of implementing and then assessing.