The new age of Energy Certificates for Buildings
Display Energy Certificates will, in due course, show the current energy performance of a building and how it has changed over the previous two years.
Do you know your EPCs from your DECs? John Fallon unravels the jargon and outlines the two new types of certificates, when they apply and their significance.Part L of the Building Regulations implements the European Performance in Buildings Directive (EPBD) in the UK and introduces two new types of energy certificates for commercial buildings. While some certification is already in place for dwellings (i.e. housing), new certificates come into force for non- dwellings (i.e. commercial or industrial buildings) from 8 April 2008. Energy Performance Certificates
Energy Performance Certificates (EPCs) have received the most attention so far. This is mainly because they already apply to dwellings and are required as part of the planning process. EPCs grade performance on a scale from A to G, similar to the system used for grading white goods. EPCs are asset certificates, in that they measure the intrinsic energy performance of the building fabric and fixed building services based on its design. They do not reflect actual energy used, but instead are based on an assumed usage pattern for the building. The purpose of EPCs is to encourage better buying behaviour in both building owners and tenants. An EPC must be shown on points of sale, lease and lease renewal and will become extremely visible to all parties. Better- performing buildings should attract a premium, thereby increasing the business case for energy-efficient buildings. Certificates are calculated using SBEM, a computer program developed by BRE that provides an analysis of a building’s energy consumption. SBEM calculates energy use and carbon-dioxide emissions of a building using a description of the building geometry, construction, use and HVAC and lighting equipment. Display Energy Certificates
Display Energy Certificates (DECs) are used to inform the occupier and the public of the actual annual carbon-dioxide emissions from the building. A key contrast from the EPC is that the DEC includes the real amount of energy consumed based on definitive meter readings. Also shown on the DEC are the operational ratings for the last two years to provide information on whether the energy performance of the building is improving or not. A DEC is valid for 12 months and needs to be updated annually. The associated advisory report will contain recommendations for improving the energy performance of the building (which is valid for seven years). DECs are intended to show the public how well the building is performing. The DEC must also show the asset rating of the building where an EPC has been provided to the occupier. As the certificate must be displayed prominently, the difference between notional performance and actual performance will be glaringly obvious to occupier and public alike. The regulations require DECs to be displayed by the occupiers of buildings with a total useful floor area over 1000 m2, where the occupier is either: • a public authority;
• an institution which provides public services to a large number of persons and is frequently visited by those persons. The former will include, for example, buildings occupied by central-government departments or their agencies. The latter would include, for example, public museums and swimming pools — but would exclude hotels and retail outlets. Delivering on the sustainable promise
Two measures of building performance: on the left is the energy-efficiency rating, which is a measure of overall efficiency; on the right is the environmental-impact rating, which is a measure of carbon-dioxide emissions. Buildings with an environmental-impact rating near the top of these scales have less impact on the environment.
Both Part L of the Building Regulations and the EPBD put responsibility for energy use firmly in the hands of building occupiers and owners. They recognise that there is little point having a well-designed building if it is not operated properly. Every building-services engineer knows that any building is a dynamic environment. Occupancy patterns change, settings drift, new equipment is installed or manual intervention turns off plant. The introduction of DECs recognises this and seeks to provide a strong impetus for delivering real energy savings. Essential to delivering ongoing savings is effective building management. At Cylon, for example, we are already seeing building and energy-management systems (BEMS) rise to the challenge and becoming the information system for energy management. The use of a modern BEMS enables real change in the operation of building services. BEMS can be used to monitor the effectiveness of change and importantly provides a mechanism for real action. Certificates will go some way to breaking the current circle of blame. Until now, occupiers have said that they would like environmentally efficient buildings but that few are available. Constructors say they could build them but they would claim developers do not ask for them. Developers in turn say they could build them, but their investors will not pay for them. Certificates will make relative energy efficiency very transparent to all parties and provide an incentive for improved performance. This valuation imperative could provide the greatest motivation to invest in energy-saving technologies and help address climate-change issues John Fallon is product marketing manager with Cylon Controls Ltd.