Unsupported browser

For a better experience please update your browser to its latest version.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

DECs show the way for measuring building performance

Non-domestic buildings account for nearly 20 per cent of the UK’s CO2 emissions. Camco’s Robert Cohen asks how it can be cut

The energy and carbon performance reporting landscape for non-domestic buildings is currently littered with new initiatives, both regulatory and voluntary. Navigating the map is complex enough even within the UK, where we have the EU Emissions Trading Scheme, Climate Change Agreements (associated with the Climate Change Levy), the Carbon Reduction Commitment, Display Energy Certificates and Company Greenhouse Gas Reporting to name but five.

Obvious difficulties are that these schemes use different CO2 intensity factors per kWh of each source of energy used and cover different scopes. For organisations with wider European or global reach, reporting complexity and cost can rise exponentially and their patience is being stretched to breaking point.

For those of us providing monitoring and targeting services as well as corporate emissions reporting, additional requirements can also be a little exasperating, as when we add yet another reporting protocol to our software to meet client needs in one particular sector or country. Wouldn’t it be nice if the world would agree a universal carbon price set by the scientists and economists? But a global treaty to limit carbon dioxide emissions looks unlikely any time soon.

The energy use of most non-industrial organisations is dominated by their use of buildings. A focus on individual buildings, as provided by Display Energy Certificates (DECs), is the level where specific energy savings can be identified and acted upon. The energy performance of buildings is easy to measure, benchmark and improve – or at least it should be. 

For new buildings, difficulties begin with the performance predictions required by regulations as part of the design process. Unfortunately, and to the dismay of many clients, compliance does not necessarily lead to good performance in use. This is not inevitable, but the calculations done for Regulations do not actually seek to predict performance in use, and nor do most design teams. However, Camco has been developing a tool to do just this on behalf of CIBSE and the Technology Strategy Board, in support of their £8 million Building Performance Evaluation programme.

For existing buildings and new buildings in operation, energy performance can be evaluated at several levels. The most basic is the DEC, currently mandated for Public Buildings over 1,000 sq m of floor area, but increasingly used by the commercial sector on a voluntary basis. A DEC enables you to identify the better and worse buildings in your portfolio and to find out if their good or bad performance is due to heating or electricity use.

Having set priorities, usually the highest energy users or worst performers, a little more analysis using the same new software can diagnose what to do about it. The task is made easier in more recently completed and more complex buildings, as they should have half-hourly sub-meter data.

This can help to produce a fairly accurate model of annual electricity and fuel consumption, broken down by end-uses such as heating, fans, chillers, pumps, lifts, ICT, etc. The breakdown is done by listing all the energy-using plant and equipment on each sub-meter, their power ratings and hours of use and reconciling the resultant energy use with the measured value.

As well as revealing some obvious targets for savings, such as equipment running 24/7 that is only used during occupancy, this analysis also provides real values for system performance in use, which can be compared with the design intent and/or with industry benchmarks. This helps the client understand the gaps between expected performance and actual outcomes and often identifies energy efficiency measures for specific items of equipment.

Many measures are zero or low-cost improvements in controls and operation; others may require investment. The model can be adjusted to show the impact of each measure and to calculate a potential improved annual performance. As measures are implemented, it is possible to set a target energy use for each sub-meter on a monthly, weekly or even hourly basis, which enables active energy management.

Energy use in and by non-domestic buildings accounts for nearly 20 per cent of the UK’s total CO2 emissions. These buildings can easily be made much more energy-efficient and now there are the tools to understand how. Let’s get on with it.

Robert Cohen is technical director at energy and emission reduction company Camco

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions.

Links may be included in your comments but HTML is not permitted.