1. Contract: EIE/07/069/SI2.466698 Duration: October 2007 – March 2010Version: March, 2010 Measured energy performance of buildings: CEN standards EN 15603 and EN15217 describe how to assess the overall operational energy use of a building Robert Cohen Camco, UK robert.cohen@camcoglobal.com

2. slide 2 Outline The EU CENSE project Measured energy performance - Rationale Differences from calculated performance Principle of the method: defining actual energy use Principle of the method: defining a benchmark Improving operational energy performance A practical tool for energy management

3. slide 3 The EU CENSE project (Oct. 2007 - March 2010) Aim of the project: To accelerate adoption and improved effectiveness of the EPBD related CEN- standards in the EU Member States These standards were successively published in the years 2007-2008 and are being implemented or planned to be implemented in many EU Member States. However, the full implementation is not a trivial task Main project activities: A.To widely communicate role, status and content of these standards; to provide guidance on the implementation B.To collect comments and good practice examples from Member States aiming to remove obstacles C.To prepare recommendations to CEN for a “second generation” of standards on the integrated energy performance of buildings

4. slide 4 Brief introduction A brief introduction to the CENSE project and the CEN-EPBD standards is provided in a separate presentation:

5. slide 5 More information More information and downloads: www.iee-cense.eu Disclaimer: CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI2.466698. The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein. Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.

6. slide 6 Why measured energy is important For existing non-domestic buildings, calculated (asset) ratings can be expensive to undertake and of limited accuracy: –Design and refurbishment data are often unavailable –Buildings and services do not behave as designed –Calculations cannot account for controls that don’t work properly or a lack of user understanding Measuring the energy used over a year is easy and inexpensive Annual renewal of a measured energy certificate is a cost effective way to motivate management, building operators and occupiers to improve their operational performance For a portfolio of buildings, measured energy certificates provide a simple, low cost means to prioritise action on specific buildings Reducing actual energy consumption is the real goal of EPBD and all related activities

7. slide 7 Differences from calculated performance Unlike a calculated rating, a measured rating captures all the energy used in a building, including office equipment, electrical appliances and catering, not just the theoretical energy needed by building services for a standard occupancy and hours of use Energy certificates based on measured energy can show the following energy performance indicators: The total weighted energy per unit floor area eg kg CO2/m2/year A numerical rating (or class/grade eg A to G) as a non-dimensional index relative to a benchmark and/or as an absolute value Electricity use in kWh/m2/yr and its rating relative to a benchmark Fuel/thermal use in kWh/m2/yr and its rating relative to a benchmark The total absolute weighted energy eg tonnes CO2/yr The energy performance for previous years

8. slide 8 Relations with calculated performance Measured energy performance is not a replacement of calculated energy performance and is not in conflict with it. They are complementary and both are needed Benchmarking measured energy performance indicates how much energy might be easily saved, but does not provide bespoke suggested improvements for an individual building Calculated performance can be validated by measured performance. A calculated performance, without reference to measured data: –If overestimated, may show cost effective improvement opportunities that are actually not –May miss improvement possibilities due to effects that are not taken into account in the calculation (simplified methods) –Always misses effects of actual system malfunctioning and of unexpected or unintended occupant behaviour

9. slide 9 How to assess and report measured energy Measured data should be adjusted to 365 days Adjustments should take account of the weather dependency of heating and cooling energy The measurement period for each energy carrier must satisfy requirements for tolerance (365 ± n days) and synchronicity with each other The energy used by a special energy use not taken into account in the building’s benchmark should be deductable if it is sub-metered before making comparison with the benchmark The energy use of the building can be expressed as a single parameter using units of primary energy, carbon dioxide emission or other energy carrier weightings defined by national policy. The energy supplied by active renewable energy sources should be reported as a supplementary value. The total energy used by the building systems, including any renewables, defines the building’s energy efficiency

10. slide 10 Principles of the method: defining a benchmark A taxonomy of building categories (offices, schools, hotels, supermarkets, etc.) must be developed for the specific purpose of benchmarking measured energy. Ideally data are collected from a significant sample of each building category over a trial year to generate up-to-date and reliable benchmarks. Benchmarks can account for climate, hours of use and occupation density Benchmarks should be expressed in terms of delivered energy used per unit of floor area (kWh/m 2 ), separately for electricity and non-electrical energy. For mixed-use buildings (comprising more than one benchmark category) the metered energy should be compared with an area weighted average benchmark. Mixed-use benchmarks can apply to sites served by common energy meters, if no more than one building has an area over 1,000 m 2 (CEN Standard EN 15217). Whole-site energy certificates –capture the total carbon footprint of the site –align the system boundary with the energy meters –subject the whole site to energy efficiency scrutiny –can be displayed in the public reception areas for the site and give the most meaningful information to the public

11. slide 11 Improving existing building operational energy performance Start with zero cost fine-tuning and better control, management and maintenance by managers, users and contractors Give priority to the role of the building manager. This person needs enthusiasm, commitment, motivation, charisma and authority to make sure energy efficiency happens. Sustainable operation of buildings must be a key performance indicator Encourage energy-wise occupant behaviour Use energy cost accounting which ensures those making savings get financial benefit Tackle incorrectly or inefficiently programmed HVAC and lighting controls resulting from poor commissioning, lack of understanding of design intent, set points adjusted liberally in response to complaints or one-off events and not reset Sustain no- and low-cost measures by an annual renewal of the energy certificate Lastly, consider a gradual programme of investment in new, more efficient plant, controls and fabric to deal with inefficient equipment, bad design, unmaintainable plant, poorly located or insufficient sensors, poor zoning, conflicts or self- contradictions in design intent and so on.

12. slide 12 A practical tool to report and check measured energy The energy signature method (EN 15603 Annex B) is a practical tool to help identify the actual energy performance of buildings, separate the influence of weather and help with energy conservation measures follow–up An energy signature plots average delivered power to the building versus average external temperature based on some readings of the energy meters and enables: –The generator sizing to be checked at the design external temperature –The effect of any operational change to be graphically highlighted –Checks on whether design objectives have been reached, by plotting actual operation on the design energy signature.

13. slide 13 More information More information and downloads: www.iee-cense.eu Disclaimer: CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI2.466698. The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein. Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.