Keeping control of your renewable technologies
As the use of building integrated renewables grows, it is important to ensure that these technologies are integrated into the building-services system — and correctly measured, monitored and managed.
Anyone who visited Ecobuild 2012 in London will have seen how the renewables sector is growing, both in terms of the products on offer and the level of interest in low- and zero-carbon technologies. Awareness of sustainable buildings is high, and looks set to stay that way for some time to come.
The use of building-integrated renewables poses a number of opportunities and challenges for designers and building operators. Renewable technologies allow building owners and operators to reduce their carbon footprints and save money by reducing their fuel bills. Legislative drivers such as the policy aspiration of zero-carbon commercial buildings by 2019 and tougher carbon targets in Part L 2016 and 2019 will make use of renewables far more likely in the near future.
The wide range of these technologies mean that it is more important than ever to make the correct choice for a particular project. Deciding between ground-source heat pumps, solar thermal, solar photo-voltaic, biomass boilers, wind turbines (or a combination of these) is not simple.
However, once the choice is made there is another significant step to consider — how to integrate these technologies into the building to maximise their impact on energy use and carbon emissions.
Jon Kilpatrick, director of systems integration specialist Detail Design Engineering, says, ‘I have visited sites where the renewable technologies are treated as being separate from the rest of the building-services system. That should not be the case if the client is to gain the benefits of their investments.’
Identifying a strategy for integrating renewables is key to success. The objective should be to maximise the use of renewable or low-carbon energy sources. At the same time fossil fuel-based systems should only be used when necessary, and the building should also be able to react to external conditions to ensure that energy is not used unnecessarily, as suggested below.
• Boilers should not operate when it is better to utilise the solar-thermal system.
• A building should react to falling external temperatures to reduce the need for heating.
• External air should be heated before entering the building.
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| Renewable technologies should not be treated as being separate from the rest of the building-services system. |
These strategies require the application of building controls and building energy management systems (BEMS).
‘The system needs to be viewed holistically,’ says Jon Kilpatrick. ‘There is no value to the client or the environment in setting up a biomass boiler to run without any links to the BEMS. It must be part of the overall system so that it can operate at maximum efficiency.’
One of the main concerns when selecting renewable-energy technologies is the potential payback period. There can be no doubt that renewables represent an investment by the client, whether for new-build or retrofit projects. The ability to measure the performance of these technologies is therefore crucial.
‘Unless you are measuring and monitoring the energy used, produced or saved, it's impossible to put an accurate figure on how well renewables are working in a building,’ says Ian Ellis, president of the Building Controls Industry Association and marketing manager for Siemens Building Technologies UK.
‘There is a lot of talk about payback times when investment is made in renewable technologies, but there is no way to calculate this if you are not measuring and monitoring the energy produced or used by the on-site renewables,’ he adds.
The holistic approach to sustainable buildings has been widely called for. Organisations such as the Building & Engineering Services Association (B&ES) have also said that integration of renewables is vital to ensure good building performance. But the building energy management system does not simply bring the different parts of the HVAC system together, it should also ensure long-term efficient and effective operation.
The Carbon Trust recognises the potential for renewables, but also emphasises the need to make a strong long-term business case for this sort of investment. Using data from a BEMS allows operators to see just what they are getting for their money — which in the case of retrofit before-and-after analysis would be impossible without this data.
‘We see that projected fossil-fuel price rises are driving people to examine the case for renewables, and as the costs of traditional fuels rise renewables become more attractive,’ says Ian Ellis. ‘But this means that managing the performance of these new technologies is more important than ever.’
