SBEM Calculations made Easier

SBEM Calculations are a method of showing compliance with Part L2: Conservation of Fuel & Power, of Building Regulations for non-dwellings otherwise known as commercial property. SBEM calculations look to evaluate that the ‘actual’ building concerned performs better, in terms of efficiency, than a ‘notional’ building which conforms to the current standards set by Legislation. The notional building is the same size and orientation as the actual building and the activities performed within each individual zone are also identical, the only things that do differ are the percentage glazing used within the calculations and the M&E services such as heating, cooling, ventilation, hot water generation and lighting.

Within the SBEM Calculation the notional building will present a Target Emission Rate (TER) in KgCO2/m² per annum and as this suggests this is a target that the actual building must not be greater than in order to demonstrate compliance with Part L2 of UK Building Regulations. The actual building will present a Building Emission Rate (BER), if BER ≤ TER then the building concerned complies with the regulations and the SBEM Calculation is successful.

There are a couple of other hoops that must be jumped through in order to gratify Building Regulations such as limiting u-value standards W/m².K for all external elements, efficiency of heat sources, power consumed through mechanical ventilation, lighting and air tightness of the building. The SBEM Calculation report will demonstrate whether these factors have been met.

Producing a building which merely complies to minimum standards will almost certainly not be enough to give a successful result of any SBEM Calculation, Building Regulations   have sought to vastly improve energy performance of new buildings in the UK and minimum standards must be largely improved upon in order to achieve a favourable outcome. Whether it is improved u-values, air tightness or lighting efficiencies which are implemented, a situation of robbing Peter to pay Paul is often the case which we at L2 Energy see on a daily basis.

On many occasions properties will not pass an SBEM Calculation without the introduction of renewable energy such as Photo-voltaics, Air or Ground Source Heat Pumps, Solar Thermal or Combined Heat and Power (CHP) Plant, all of these can be modelled into the SBEM calculation tool to identify the most suitable solution for a given site and client.

To achieve success in executing an SBEM Calculation it is prudent to make the building as thermally efficient as economically possible in the first instance, this will provide an excellent starting point. Ensure that the building has excellent air tightness of around 5 m³/hr.m² at 50pa or less. Following this, efficiency of m&e installations is key. The most thermally efficient building is only as good as the efficiency of the systems within so ensure that the lighting loads are optisimised with technologically advanced switching applied and heating and cooling efficiencies are maximised within budgetary constraints.

L2 Energy Consulting have a huge wealth of experience in achieving compliance for a whole manner of differing building types from schools, hospitals and leisure to 10 storey office blocks, flagship industrial facilities and large hotel developments. Whatever the scheme, we will find a solution.

Visit www.l2energy.co.uk/sbem-calculations.html for further information on SBEM Calculations and obtain a competitive quotation.

Energy Statements Explained

Energy statements for planning are becoming much more of a requirement when filing a planning application for a suggested new development to a Local Authority for approval. Each individual Local Authority will have their own twist on what is required before the application will granted and the development can begin.

So what is an Energy Statement?

An Energy Statement is a document which demonstrates to the planning authorities that a proposed development is conscious of the environmental impact, in terms of carbon dioxide emissions, that the new building or buildings will produce and the proposed measures which are to be taken to decrease co2 emissions from new development.

Many authorities will put their own stamp on what their requirements are. This will almost certainly include the use of on-site renewable energy sources and from which between 10-20% of carbon dioxide emissions will have to be lowered by their use; the percentage requirement will come down to individual  authorities. The Energy Statement should talk about the types of Renewable Energy options available and their appropriateness for inclusion within the new development and thereafter an assessment of the carbon savings anticipated via the chosen technology or technologies to be included.

Reducing Carbon emissions is not all about the inclusion of renewable technologies though and many local authorities recognise this and require a more rounded approach to be taken. This is often demonstrated by the use of a so called ‘Energy Hierarchy’ approach.

Stage 1 of the ‘Energy Hierarchy’ is Improvements to building fabric; this looks to go beyond UK Building Regulations for thermal efficiency of fabric or U-values as they are technical known. The minimum U-value of an External Wall in the UK under 2010 Regulations for commercial property is 0.35 W/m².K, for Ground Floors and Roofs the minimum standard is 0.25 W/m².K and for Windows and Doors the minimum standard is 2.2 W/m².K. With more advanced building products coming to the market place every month these minimum standards can be greatly improved upon and it is not uncommon for an External Wall U-value to be as low as 0.18 or better, Floor and Roof down to 0.14 and Windows and Doors down to 0.9 W/m².K, the lower the U-value the more thermally efficient the element is. Improvements to Air Permeability can also play a part in the equation, Building Regulations require a minimum Air Permeability of 10 m³/hr.m² for a new commercial building greater than 500m², with buildings being capable of achieving air tightness of below 3 m³/hr.m² when built to high standards, this can reap considerable rewards. In summary by improving the thermal efficiency and air tightness of a building, huge reductions in carbon emissions can made.

Stage 2 of the ‘Energy Hierarchy’ considers the efficiency of the Mechanical and Electrical (M&E) Installations that are to go into the property, by maximising the plant efficiency such as boilers, air conditioning, hot water storage, mechanical ventilation and lighting, obviously this will have a huge impact on carbon emissions of any proposed building, whilst minimum standards have to be met to achieve Building Regulation compliance stage 2 of the ‘Energy Hierarchy’ seeks to go well beyond minimum standards to further reduce co2 emissions.

And finally Stage 3 of the ‘Energy Hierarchy’ Renewable Energy, following improvements to the fabric thermal efficiency and then to the efficiency of the M&E installations the planning authority will seek further reductions in co2 emissions through the use of renewable energy sources. Renewable Energy Sources investigated for their feasibility into a scheme usually include Photovoltaic’s (solar panels), Solar Thermal (solar hot water installations), ground source heat pumps, wind turbines and Combined Heat & Power (CHP) installations. Each of these may have their place in a scheme but may also be ruled out due to site constraints such as overshadowing from adjacent buildings or trees, limited clear wind path again due to adjacent buildings or trees, or feasibility may be discarded due to good old fashion cost restraints.

Whatever the requirements are of the individual UK Planning Authorities; L2 Energy Consulting will have come across them before and will have the necessary expertise to provide the calculations and advise required to satisfy their needs to a successful outcome. For further information regarding our service in this area please visit www.l2energy.co.uk/energy-statements.html We will be happy to share our expertise with you.