The two responses to climate change
• Adapting to the climate change that is already inevitable.
• Mitigating against future change by reducing CO2 emissions. And if we are to do that effectively, we need to take a long hard look at the way we design building services. For example, traditionally we have effectively been historians designing for ambient conditions that have gone before. Now we need to become futurologists, using sound scientific evidence to predict the future ambient conditions that could become the norm. At the same time we have to take account of scientific uncertainty and public attitudes and values. So, rather than designing for ambient temperatures of 28ºC, perhaps we need to design for 32ºC — or even higher in urban city centres. Rather than designing chillers to trip at 35ºC, we should be looking at 45ºC. In parallel with this adaptation in design, building services will play an increasingly important role in mitigating the effects of climate change. For example, the Government’s targets aim for all new homes and new schools to be zero-carbon by 2016, with the same aspirations for public sector non-dwellings by 2018 and other non-dwellings by 2019. At the same time, we have to apply the same innovative approaches to existing buildings, where most energy is used. In fact, as buildings become more efficient, the ratio between build energy and operational energy is going to change, so the embedded energy becomes more significant, and there will be less justification for demolition and new build. Instead, we can anticipate re-using buildings much more — perhaps changing their function and certainly improving their energy performance. All of which means we are going to have to make much more extensive use of renewable energy sources in the future. This is borne out by the UK Renewable Energy Strategy consultation document, published in June of this year. This document follows on from the Energy White Paper, which had to be modified by European targets, for 15% of all energy to come from renewables by 2020. Only 20% of this is to be achieved from transportation, a figure that is likely to fall if the current concerns about biofuels are sustained — putting a significant onus on buildings to do their bit. Major contributors to this are wind (19% offshore, 13% onshore), biomass heating (15%), solar thermal (9%) and biogas heat (5%). So there is going to be considerably more emphasis on electricity in buildings and a key role for building-services engineers is to incorporate more energy generation in buildings. While one option is to put a small nuclear reactor in every building, I think we can be pretty certain that broader use of solar photo-voltaics (PV) will be more acceptable. In fact, some forecasts suggest that we could be deriving 50% of our electricity from solar PV by 2100. For that to happen, solar PV will not only have to become more efficient, but also much cheaper to provide a sensible payback. Given that solar PV is already a third of the price it was 20 years ago and considerably more efficient, that seems eminently achievable. Consequently, we also have to find better ways of storing electrical energy generated by these very variable sources. Battery technologies are certainly improving very rapidly, and there is also the option of making more extensive use of fuel cells. For instance, when there is a surplus of electricity on a sunny day it can be used to electrolyse water. The resultant hydrogen and oxygen can then be stored in separate vessels for use in fuel cells when there is less solar energy to drive the PVs. And the same principles can be applied to wind and tidal energy on a larger scale. In the shorter term, there will still be demand for traditional plant such as boilers and chillers, so we need to ensure these are the most efficient available and linked to efficient control systems. Looking further ahead, as we become more comfortable in our ‘futurologist’ role, we must embrace new technologies in an inventive and pioneering spirit. At the moment, we are being forced into this role through policy and legislation. But now is the time to seize this opportunity to lead the way through a more pro-active mindset that reflects the very best in building-services engineering. Ant Wilson is a director with Faber Maunsell.