Building an energy efficient and sustainable future. By Marcus Eves
The development and adoption of energy efficiency and sustainable solutions have been driven by environmental, political and financial factors.
It is common knowledge that the built environment is one of the biggest users of energy, accounting for 37 per cent of total UK greenhouse gas emissions in 2012. Residential emissions accounted for 66 per cent of all buildings emissions, with commercial and public sector emissions accounting for 26 per cent and eight per cent respectively. They comprise 45 per cent direct CO2 emissions (i.e. from burning fossil fuels) and 55 per cent indirect (grid electricity-related) emissions.
Since the Kyoto Protocol was signed in 1995 the UK Government has taken a number of steps to show its leadership in tackling climate change. The Climate Change Act was passed in 2008, setting a framework to develop a path to the reduction of emissions. A legally binding target of cutting greenhouse gas emissions by at least 80 per cent from 1990 levels by 2050 was also introduced.
The Government is therefore keen to encourage homeowners, businesses, property developers and commercial tenants to manage their energy more efficiently – a move that will also benefit them all individually as well as us all collectively.
The need for energy efficiency
There are a number of reasons why we need to invest in a more efficient future. Currently the global economy relies on fossil fuels – almost 80 per cent of all energy consumed is generated through the burning of fossil fuels. This is creating an increased CO2 concentration in the atmosphere and in the oceans. This has led to heavier and more frequent extreme weather, increased global temperatures, melting ice caps and rising ocean levels.
The fossil fuels we rely on are a finite resource. As the amount of fuel available decreases the price increases. It will be expensive to mainly rely on fossil fuels in the future. Furthermore, as the population increases strain on fuels also goes up. Without energy efficiency measures in place this would add to the rising costs of a limited resource.
Fortunately, energy efficiencies are readily available and provide numerous benefits. To be efficientonly requires small additional upfront costs. Generally the payback periods are short and initial investment is returned through lower fuel bills or government financial incentives such as the Feed-In Tariff. Encouraging energy efficiency also drives innovation forward, ensuring we continue to develop energy and cost-saving products and processes.
How to be efficient
There are two steps to increasing energy efficiencies; reducing energy use and improving energy use.
For the first element, it is quickly apparent that the simplest way to save energy in a building is to avoid using it in the first place.
The second is achieved through delivering the generally accepted definition of energy efficiency: ‘using less energy to provide the same service’.
The following steps help to achieve both parts:
Measure and Meter
You can’t reduce or improve what you don’t measure. Understanding when and where most energy is being used and how much it’s costing you is a good first step to adapting your energy consumption to provide longterm carbon and financial savings. Having accurate and real-time information about a building’s energy use enables you to make informed decisions about your energy behaviour.
Minimising fabric heat loss is integral to increasing energy efficiencies. Nearly every building in the UK has a heating system so it is essential to understand how the building performs thermally.
Heat will always flow naturally from a warmer to a cooler space. The heat will move directly from all heated living spaces to the outdoors and to adjacent unheated lofts and garages – wherever there is a difference in temperature.
Understanding and quantifying energy usage, heat loss and airpermeability will be the first steps to insulating, making your building more comfortable by helping tomaintain a uniform temperature and making walls, ceilings, and floors warmer in the winter and cooler in the summer.
Heating and cooling
Once the best possible standards of insulation and air-tightness have been achieved the space heating loads should be determined. A heating system should be adequately sized to meet the demand of the building. Under or oversized heating plant will consume much more energy than boilers correctly sized to match the anticipated space and domestic hot water demands.
Modern domestic ErP boilers can be expected to achieve efficiencies of up to 90 per cent, while commercial boilers can see efficiencies around 95 per cent. Incorporating advanced controls such as delayed start thermostats or weather compensation will lead to even better efficiencies.
The energy consumption of lighting in residential buildings is estimated to be between 10-15 per cent of all energy demands and in non-domestic buildings this figure is in excess of 25 per cent. Efficient LEDs are recommended to be used to replace all tungsten and compact fluorescents.
In commercial buildings absence and presence detection should be considered in areasof low-transient occupancy.Photoelectric controls can beused to automatically dim the lights based on the availabledaylight – ideal for buildings with large amounts of glazing.
Renewable Energy & Green Technology:
The national grid delivers approximately 37 per cent of the primary energy input as electricity to the end user, the rest is wasted. A number of technologies are readily available which the Government is promoting to tackle this problem and increase local onsite generation.
Photovoltaic panels are readily applicable to most buildings and easy to fit as part of a new build or a refurbishment. With the Feed-In Tariff payments these are desirable as payback can be achieved in less than ten years. Wind turbines have been round for years, but these are far moresuited to larger applications, aslarger turbines are more efficient. Smaller turbines are usually inappropriate in urban areas as these raise planning issues.
Ground source heat pumps and air source heat pumps are great for off gas buildings. With advances in technologies, some system efficiencies are reaching in excess of 300 per cent. Although the capital costs can be high, if sized and operated correctly energy consumption can be significantly reduced.
Heat recovery systems are starting to push their way into the market place and for good reasons. Their main focus is to retrieve and recycle energy, which would usually be lost. The three systems are wastewater (recyclingwater usually lost down the waste)mechanical ventilation (recouping heat from the air normally sent outside through conventional extract fans) and flue gas heatrecovery (recycling heat in the flue gases to preheat the cold waterentering the boiler). Wastewater and mechanical ventilation should always be considered as part of a new development as they are not always practical to retrofit, and flue gas heat recovery is suggested with every boiler replacement.
There is a huge range of readily available options to improve energy efficiency. The challenge is to select the solution/s that achieve the maximum results with minimal costs.
Marcus Eves is Sustainability Consultant at Darren Evans Assessments. Darren Evans is an expert in sustainability and energy efficiency.Working for large commercial developersthrough to independent investors with a small private rental portfolio, architects, house builders and public sector organisations, Darren Evans can provide an energy efficiency service that meets clients’ precise requirements.
For more information, please see www.darren-evans.co.uk