Controls for energy efficiency

As we strive to reduce building energy use in tough economic times, BCIA President Ian Ellis highlights just how cost effective building controls are, and why building managers should put them at the heart of any energy-saving strategy.

As the recession bites, government has less money available to incentivise low-carbon solutions, and at the same time, businesses are faced with growing energy bills. The drive to find cost-effective solutions to the challenge of energy efficiency is gathering pace.  In December 2010, the Carbon Trust said that the UK public sector could achieve net savings of £1 billion through energy efficiency schemes, highlighting just how much potential there is in simply reducing the amount of energy we use.

Energy saving is also now recognised as playing a crucial role in reducing the CO2 emissions created by the UK’s commercial building stock. Not only is saving energy beneficial to the environment, it is also generally a much cheaper first option than the application of sustainable technologies. Reducing energy waste is also the most effective first-step for decarbonising and improving our existing building stock – which will outnumber new-build for several decades to come.

In 2007 the Defra UK Energy Action Plan stated: “Using energy more efficiently is the fastest and most cost-effective way of cutting carbon dioxide emissions. It can also improve productivity and can contribute to the security of our energy supplies.”

More recently, in November 2010, the EU Parliament passed a resolution stating that: “Energy efficiency should be a key priority of Europe’s energy strategy for 2011 to 2020.”  In fact, the EU seems to regard energy efficiency as the solution for many climate-related and social problems: “Energy efficiency is a cost-effective way to cut energy dependency, combat climate change, create jobs and curb energy bills.”

One of the many benefits of building controls is that they are now offered in a wide range of options for end-users, so they can be specified to exactly match the requirements and budget of any new-build or refurbishment project. Open systems, such as BACnet, LonWorks, KNX and others, also make linking together different types of control much more straightforward. This means that today’s controls are a cost-effective and flexible solution for building managers looking to build an energy efficiency strategy.

But it is this range of choice that can create the challenge for specifiers and end users. How best to achieve energy efficiency within budget? What type of control systems will achieve the level of energy efficiency required for a building? And perhaps the most important question today would be, what is the payback period for my investment?

Anyone looking for answers to these questions, would do well to start with a little-known Standard, BS EN 15232: Energy performance of buildings – Impact of building automation, control and building management.   EN15232  is one of a set of European standards designed to support the European Directive on Energy Performance of Buildings (EPBD).   It defines the minimum levels of building controls required to achieve different levels of energy efficiency in a number of building types.

The standard was developed using advanced building simulation modeling, so it can be used as a tool to qualify the energy efficiency of building control and BEMS projects. This means that it is also possible to quantify the benefits of different levels of building control – putting specification and calculation of payback periods on a much firmer footing.

For facilities and energy managers, EN 15232 assigns classes A, B, C or D to levels of control within a building, and shows the resulting energy efficiencies that could be expected.  The main areas of building services are covered, including control of heating, cooling, ventilation and air conditioning, and lighting. For every area different levels of control are assessed. For example, for heating control the analysis starts with ‘no control’ on the heating system – the highest supply output is continuously supplied, resulting in the emission of unnecessary heat at partial loads. Other levels of control are then considered, from central automatic control that reduces energy losses at partial load, through to integrated individual room control including demand control based on occupancy or air quality.

This is an invaluable tool for those looking to balance capital investment against long-term energy savings. It also makes specification of BEMS a much clearer process for everyone involved, from the end-user client to the installer.  The BCIA is recommending use of EN 15232 for specifiers and end-users planning a building controls or BEMS project. Not only does the standard give a clear indication of energy savings that can be expected from the use of controls, it also offers a common language for specification.

BS EN 15232: What savings can be achieved using building controls?

According to this Standard, there are substantial energy savings to be made from upgrading building controls. The Standard highlights the fact that demand-centred controls not only create more productive and comfortable environments, they also ensure that building services such as heating, cooling, ventilation and lighting are not used unless they are required. The types of saving that can be achieved are summarised as:

Offices: 39%

Shopping centres: 49%

Schools/universities: 34%

Hospitals: 18%

Hotels: 25%

Restaurants: 31%