The UK government has recently announced plans to reduce Britains carbon emissions by 18 percent by 2020. In view of the fact that nearly half of all energy consumption is related to the operational use of buildings, and in a bid to successfully meet these targets, government guidance and legislation is therefore putting emphasis on the need to improve the energy efficiency of buildings as a means of significantly reducing emissions.
In direct response to this, Corus Colors is about to launch a new technical paper - An approach to low carbon buildings - providing guidance and advice on the practical measures that can be implemented at the design stage of any building to effectively improve energy efficiency and reduce the associated CO2 emissions. Ian Clarke, Applications Development Manager at Corus Colors, provides an overview.
Addressing the energy performance of a building at its concept design stage can result in the finished structures operational energy demands being significantly reduced helping to minimise its carbon footprint. Key to achieving this is looking at how factors such as location, shape, size, layout and orientation of the building can contribute to reducing the requirement for artificial lighting and ventilation. Whilst care always needs to be taken to avoid compromising the functional performance of a building, by seeking to address these physical aspects at the design stage, designers can then go on to develop an energy reduction strategy. This strategy then forms an integral part of the whole design process and ultimately creates significant benefits that can be realised throughout the useful lifespan of the building. The four main issues in order of consideration are:
1. Reducing service demand careful assessments of the requirements for the internal operating environment can have a very significant reduction in energy demand and CO2 emissions. Factors such as internal temperature and control parameters, ventilation, humidity and internal lighting levels all have a big impact on the service energy demand. It therefore makes sense to ensure the first priority is to minimise the demand for heating, ventilation and artificial lighting through a combination of efficient building design and energy conscious building use.
2. Optimising envelope efficiency minimising heat loss through the building envelope is priority in any building design, as an effective solution will automatically reduce the need for artificial heating systems along with the associated energy consumption. Designers can therefore seek to optimise design of the building envelope to balance heat losses and solar and lighting gains through detailed consideration of insulation, air-tightness, minimisation of thermal bridges and incorporation of rooflights.
3. Maximising service efficiency having taken the necessary steps to minimise both the demand for and waste of operational energy wherever possible, the next priority should always then focus on specifying the most energy efficient means of delivery of heating, lighting and ventilation.
The best choice of mechanical and electrical (M&E) plant varies from one building to the next based on individual building specifics such as roof height, requirement for ventilation etc. For instance, there are several technologies available for supplying heat into a building i.e. windfarm air heaters or radiant tube heaters whilst each brings with it associated benefits in terms of energy reduction these advantages will be realised to varying degrees depending on the individual building.
4. Sourcing low-carbon energy regardless of whether a building has been designed to minimise its operational energy requirements, with the most efficient delivery mechanisms for intended building use having then been specified, it is inevitable that there will always remain a residual demand for energy that requires electrical power and heat.
In order to truly minimise operational CO2 levels and create a low carbon buildings, it therefore becomes necessary to identify an eternal source of energy that generates either no or low levels of CO2 emissions. Solutions available include photovoltaics, wind turbines, solar thermal panels and heat pumps, and whilst these typically have a relatively high outlay cost, the long term savings that can be made both financial and energy related - mean that this can be balanced out over a relatively short period of time.
In designing low carbon buildings there is a clear hierarchy for the designer to follow first to minimise the requirement of servicing, optimising the building envelope, then to use efficient servicing strategies, and finally sourcing the residual energy requirement from, as far as is possible, a low carbon or renewable channel. Not only will this enable designers and building owners to meet the minimum requirements for energy efficiency as stipulated by governing legislative requirements, a correctly implemented strategy that actively seeks to optimise operational performance can also serve to future proof that building against any changing requirements in the future.