Increasingly local planning authorities in the UK require an energy statement to be submitted as part of a planning application. This is often combined with a requirement to provide a reduction in carbon emissions from the energy use of the building through onsite generation of energy using low or zero carbon technologies (often referred to as renewable energy technologies). Typical reduction targets are currently between 10% and 20%. For larger development proposals the preparation of an energy statement requires a thorough option study in the form of a renewable energy feasibility study. For small residential developments the options are limited. This article provides information about preparing an energy statement for small development proposals: typically one or two houses. In preparing an energy statement five steps should be followed:
Determine the target energy performance Identify the energy performance of the building envelope Consider supplementary energy saving measures Estimate the energy performance Consider low or zero carbon technologies
Following these logical steps and writing it down in a statement will provide you with an Energy Statement that can be submitted with your planning application.
Determine the target energy performance
The first step is to define the energy efficiency of the building in terms of the carbon emissions that is going to be achieved. Part L of the building regulations introduces two terms that are being used in determining the energy performance of a building. These are Target Emission Rate (TER) and Dwelling Emission Rate (DER). These two values are determined using the set of SAP calculations that is made available by the government. Part L of the building regulations require that DER is not greater than TER.
Improve the energy performance of the building envelope
The first step to consider is to improve the energy performance of the building fabric. This is expressed as the U-value of the various building elements (roof, walls, groundfloor, windows and doors). Significant reductions can be achieved by specifying appropriate roof insulation, wall insulation and energy efficient windows. Other measures that improve the energy performance of the building fabric are the air tightness of the building and the ventilation characteristics. The type of fuel that will be used also has a significant impact on the carbon emissions of the building. The emission factor of the various fuel types is very different. Electricity for instance has much greater carbon emissions per unit of energy than natural gas. Clearly the use of electricity for space heating has a significantly adverse effect on the carbon emissions of the house.
Consider supplementary energy saving measures
There is a range of supplementary energy saving measures that can be implemented. The effect of the majority of these additional measures influences the behaviour of the people living in the dwelling. The actual amount of energy saving can therefore not be quantified, but these measures are thought to be useful nevertheless. Measures to consider are:
Provision of a drying space Provision of energy labelled white goods Energy efficient lighting internal and external Provision of cycle storage Provision of a home office
Estimate the energy performance
Including an indication of the expected carbon emissions in the energy statement is important for two reasons. First of all it can serve as a concluding element to the energy statement. Secondly, when the planning authority requires a certain percentage of the total emissions to be reduced through the onsite generation of energy through renewable energy technologies the expected carbon emissions will serve as the starting point for the consideration of renewable energy technologies. Occasionally reference is made to a toolkit that was published in 2004: "Integrating renewable energy into new developments: Toolkit for planners, developers and consultants". The benchmark data in the toolkit are dated and based on existing stock and therefore likely overestimates the energy use for any particular new building. We recommend therefore using actual calculations that are appropriate for the building. This should be done through SAP calculations. Even though at planning application stage the detailed design has not yet been completed, a good estimate of the value of the parameters in the SAP calculations can be made. The information that is considered in the section about energy efficiency of the building fabric should be taken into account when preparing the SAP calculations.
Consider low or zero carbon technologies
For large development plans there are many potential viable low or zero carbon technologies or renewable energy technologies available. For small one or two unit developments the available viable technologies is much more limited. The renewable energy technologies that are widely available and are viable options for small developments are:
Solar hotwater system Photovoltaic cells Ground source heatpumps Air source heatpumps Biomass heaters
In addition small wind turbines are often mentioned and progress on micro CHP is progressing rapidly.
Paul Giesberg is founder and Principal Director at Planning for Sustainability Ltd. This firm specialises in supporting organisations with meeting the challenges of sustainable development in infrastructure and real estate development projects. Among the services that Planning for Sustainability provides are BREEAM advice and assessments and energy statements.
