FOCUS ON: SUSTAINABLE SCHOOLS
Reflections on net-zero in schools N
Comment by NIGEL AYLWIN-FOSTER, ReEnergise
et-zero is a current buzzword, but it’s causing confusion. There are now two interpretations of net-zero in circulation in the energy sector, both of which are relevant for the
education sector. They mean different things and require ostensibly
different responses, but the responses overlap and with a clear focus on purpose it is possible for each school to pick the right path for its own situation.
• Net-Zero Carbon. Net-zero carbon is achieved by reducing greenhouse gas emissions (GHG) as far as possible and then using carbon offsetting to compensate for the balance. The purpose is to combat climate change.
• Net-Zero Energy. Net-zero energy means generating as much energy as is used. This does not necessarily mean a school’s energy usage is particularly low, nor that it has a low carbon footprint. A net-zero energy school will almost certainly still rely on grid power at various times of the day, but it could also be exporting power back to the grid at other times of the day (or selling it to some other user nearby): the key is the net-zero balance between the two. The ultimate purpose of this exercise is to save money: it is not about the GHG emissions, because the electricity grid is rapidly decarbonising anyway.
So, what are the implications for school estates? Let’s start with net-zero carbon. According to current national policy, every school estate in the UK will need to be net-zero carbon by no later than 2050, and for schools in Scotland that deadline is 2045. Is this achievable in practice?
It is hard to think of a school estate in the UK that could not ultimately become net-zero carbon in a pure engineering sense: the technologies are already available to cater for the conversions required. In practice, the defining issues are likely to be the budget required to achieve it, the capacity of the electricity grid to support the transition; and in many instances – particularly urban settings – the requirement to coordinate the school’s transition with the transition of the wider local community. For example, for some school estates the only practical and affordable solution may prove to be plugging into a local large-scale heat network being developed by an outside agency, rather like being plugged into the local mains gas grid at the moment. Whatever the solution for a given school estate, the initial capital outlay will be high, and whether it ends up saving a school money will in most cases depend on what happens to future grid electricity prices; and the extent to which the school can generate its own power. It begs the question, is net-zero carbon even relevant any longer given the current energy crisis
and the likelihood of much higher energy prices for the longer-term than we’ve been used to in past decades?
The answer is a resounding ‘yes’, but it may require a change of tack: reducing reliance on the electricity grid has now become much more important than it was. Step forward net-zero energy. Most school estates will not be able to achieve net-zero energy, at least within the horizon of current technologies because they will not be able to give up the space required to install the scale of on-site power generation systems required to get to net-zero energy. However, the building blocks of net-zero energy
in other school developments, the school has retained the land and installed large-scale on- site power generation and storage. The school’s heating plant has been converted to heat pumps. Outcome: as for Schools A and B.
School D. Urban. On the gas grid. No spare land. Converts the heating plant to heat pumps. No space for a solar farm but makes maximum use of available roof space to install solar PV to offset some grid procurement. With clever use of power storage and optimising energy plant running times it is also able to buy grid power at cheaper times. Outcome: net-zero carbon; not net-zero energy and energy is still a cost to the school, but much less than it would otherwise have been.
There are several other permutations on this theme, but in short, now is the time for reassessing the school’s strategy and programme towards net-zero. Financial calculations from previous years will have changed in the light of the recent changes in energy pricing. That, in turn, may well change the priority for parts of the net-zero programme. A pragmatic stocktake of the options will be required in terms of capital outlay, hassle-factor, timeframe for implementation, return on investment, whole-life costs and – of course – the impact on carbon footprint.
Trenching for GSHP System, St George’s College, Weybridge
are more relevant than ever: on-site power generation projects which were not considered cost-effective a few years ago may well be cost- effective now, simply because grid prices have increased so much.
How might all this look in practice? Cast your mind forward 20 years: here are some examples of how school estates could emerge once all this has been sorted out. These are all based on authentic assessments recently done for schools:
School A. Rural. Off the gas grid. Has spare land available. Converts the heating plant to heat pumps. Installs large-scale on-site power generation (e.g. its own solar PV farm). Installs commercial scale power storage. Still relies on the national electricity grid to compensate for lulls in its own on-site generation, but also exports excess power to the grid at other times of the day. Outcome: it is net-zero carbon and net-zero energy – the best of both worlds – saving the planet and saving money.
School B. Rural. Off the gas grid. Has spare land available. The engineering solution for its heating plant conversion is biomass rather than heat pumps. Accordingly, it has set up its own forestry operation to generate its own biomass fuel on the spare land, as well as on-site power generation. Outcome: as for School A.
School C. Urban. On the gas grid. Has spare land available. Instead of selling this land off to developers to generate a cash surplus for use
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www.education-today.co.uk Solar PV, Ditcham Park School December 2022
You can get in touch with Nigel to discuss any of the above as follows: uOffice: 01428 608462 uMobile: 07496 950531 uEmail:
nigel@reenergisegroup.com
Heat Pumps in the Plant Room, St George’s College
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