Q&A Can system data help save energy? Andy Pearson received ASHRAEs Comfort Cooling award for project excellence in 2016 for a Norway district heating system Andy Pearson All systems go CIBSE ASHRAE Technical Symposium 2020 speaker Dr Andy Pearson, group managing director at Star Refrigeration, explains what future heating systems might look like A t this years Technical Symposium taking place online on 14-15 September Andy Pearson is giving a keynote on Taming the energy tiger how can I make a difference. He says the UK has to switch wholeheartedly to electricity if it is to hit carbon reduction targets. He outlines three principles to mitigate against climate change: stop burning stuff, switch to electricity and remember the negawatt (the energy saved as a result of energy conservation). Andy Pearson studied manufacturing science and engineering at the University of Strathclyde. He joined Star Refrigeration in Glasgow as a design engineer. He had short spells as a site manager and commissioning engineer before joining Stars sales department. In his current role, he is responsible for Star Refrigeration Group as a whole. He was president of the Institute of Refrigeration in 2010 and was elected a Fellow of ASHRAE in 2016. See the keynote at cibse.org/technicalsymposium Why do heating systems need to switch to electricity? There is a three-step process of thought required: first, burning fossil fuel and emitting carbon has to be curtailed and quickly. Second, moving to the combustion of other fuels even carbon-free fuels is not the answer because it fails to address other issues surrounding combustion, such as air quality. Third, although localised generation can provide some small-scale answers, when we look at heat demand on a national scale, it is clear that moving heating onto the grid is the only solution that answers all the independent, but simultaneous, challenges. It is clean, familiar, it doesnt depend on unproved technology and it can be done quickly. But this only works if centralised electricity generation is also clean. What is the true measure of efficiency in building systems? Its necessary to divide the assessment of efficiency into two complementary components; quantitative and qualitative. The calculable efficiency is the desired effect whatever that may be divided by the energy required (the measurable input) to achieve the effect. It is difficult to quantify the desired effect for a building. The true measure of good efficiency is when all qualitative objectives have been met and the measurable input (the quantitative part) has been minimised. For example, theres no point having an energy efficient chilled water system if everybody in the building is uncomfortable. The key to getting energy use down is being able to make meaningful comparisons. This starts with the commissioning data; it should be possible to call up data on building performance when it was new and functioning as intended, and it should then be possible to maintain that level of performance throughout the building life. We now have the ability to record data at commissioning and provide ongoing comparison with current performance to highlight the areas requiring attention. The key is to make the output as simple as possible. What refrigerants should the industry be considering? On one hand, I wouldnt rule out anything but, on the other hand, I dont think building design specialists should have to worry about something as technically complex as the inner workings of the refrigeration or air conditioning system. What they need to do is to be completely honest about the order of precedence they place on the various competing factors that will apply to their project (for example capital cost, reliability, long-term security, ease of maintenance and efficiency) and choice of refrigerant will naturally follow. So, for example, if high energy efficiency is important, then ammonia should be considered but, if the overriding consideration is low capital cost, then it is unlikely to be a contender. Its important to realise that energy efficiency should not always be the number one priority for example, in a system which only runs for a small percentage of the year, it doesnt really matter but, if the load is high 24/7, then efficiency has to be much more important. Should we be moving to ambient heating/cooling networks? This is an interesting question we need to find better ways of enabling adjacent users with requirements for heating and cooling to cooperate with each other. One suggestion would be to provide a network of water at, say, 15C, which can be used as the heat sink for chiller plant to reject heat efficiently all year round and, at the same time, provides a ready heat source for local heat pumps to tap into. This would make both the chillers and the heat pumps more efficient, free up a lot of valuable real estate currently used for heat rejection equipment and the network would be in thermal equilibrium with the soil so wouldnt even need to be insulated. www.cibsejournal.com September 2020 69 CIBSE September 2020 p69 Andy Pearson QA.indd 69 21/08/2020 17:14