An Introduction to Estate Decarbonisation & How to Approach It in Schools and Colleges


Although the decarbonisation of a school estate is not the only task a school faces in seeking to becoming environmentally sustainable, it is likely to prove the most challenging, on account of being the most disruptive and expensive. It will prove to be the work of some years.
The first task is to draw up a plan: this is known as a decarbonisation plan. It needs to be comprehensive, to be of any use. It needs to identify quick-wins, and longer-term objectives: the latter likely to be those projects that will either be expensive or intrusive on the school estate.

This article explains the main items that the decarbonisation plan needs to cover. It is not exhaustive. Most schools will need external support in drawing up this plan, because they will not have the expertise in house.

Note that the UK Government is now running successive rounds of grant funding to pay for these plans to be drawn up. Likewise, the programme of projects arising from the decarbonisation plan will be eligible for further grant funding, provided the work has been scoped and specified to the necessary standards. Salix Finance administer the grant schemes and will judge each application on its merits.

The Principles

Every school estate has its own unique circumstances but school estates across the UK are subject to broadly the same challenges. Furthermore, the principles behind decarbonisation of a school estate are valid for all schools and although the energy sector in the UK is complex and can seem daunting to consumers, the task can be simplified conceptually.

There are three categories of energy usage on a school estate: these are power, heat and transport. The essence of estate decarbonisation is to render all the usage of power, heat and transport zero-carbon; or if true zero-carbon cannot be achieved, then go for net zero-carbon – which means that shortfalls are made up by some sort of carbon-offsetting.
Buy Well. Buy 100% renewably-sourced grid power. This can now be achieved at no extra cost compared to buying so-called ‘brown’ energy (derived from fossil-fuels). Buy Well, for power, is the easiest objective to achieve because with one contractual change all the school’s use of gird power becomes zero-carbon. Unfortunately the same commercial trick is not available for buying heating fuel: the only true zero-carbon option for heating is to move away from combustion methods altogether; (see ‘Generate Well’).

Use Well. Make the estate energy infrastructure as efficient as possible. The cheapest, cleanest energy is energy not used. There are some well-established measures to achieve this. For example:

  • All lighting should be converted to LEDs as soon as possible. 
  • Buildings need to be well insulated. 
  • Heating (and cooling) controls need to be set up correctly.

An energy efficiency survey by an external assessor should determine and explain all the options in enough detail to justify grant-funding applications.

Schools also need to encourage energy-efficient behaviour by the occupants. Behaviour campaigns are usually best championed by carefully selected staff and students who have a marked passion for the cause. Unfortunately it will not be enough to run the campaign for just one year: it needs to be maintained year after year as part of the way of life at the school. This part of the ‘use well’ task need not cost money: there is plenty of generic open-source material available, and several charities run framework schemes to guide schools.

Generate Well. Given that the national grid is decarbonising so fast, the ‘generate well’ tasks mainly apply to heating and transport systems, where the aim is to cease using fossil fuels. Nonetheless, on-site power generation is still relevant, largely to support the heating conversion task.


  • Converting the heating is the most challenging project, by some measure; but if not tackled, the school will never achieve net-zero.
  • The technology options are currently heat pumps or biomass. Much is spoken of hydrogen; but it’s wishful thinking to see it as a solution for heating buildings en masse in the UK. There is not the space here to go into the detail, but green hydrogen is much more likely to find its commercial role as a fuel for requirements such as heavy transport: shipping and trains, for example. 
  • Every school will need a detailed site survey by an appropriate expert to determine the optimum technology and design concept. Where possible, heat pumps are likely to be preferred. This is partly to avoid the logistic burden associated with biomass refueling; but heat pumps are also the cleanest means of generating heat. They have no emissions on site; and if powered by renewably sourced electricity they are effectively zero-carbon. 
  • Contrary to popular belief, it is not necessary for a building to be stripped out, re-insulated and have underfloor heating, for heat pumps to work. There are plenty of examples of ‘energy-leaky’ buildings where heat pumps function well. The important thing is to get the specification right and then ensure the installation is built as-specified; with no short-cuts by contractors.


  • Even though net-zero grid power is now easily purchased, it is also usually an advantage to install on-site power generation, possibly combined with power storage[1]. This reduces the school’s reliance on the grid; and in time will reduce operating costs. 
  • With or without additional power generation on site, available grid capacity can prove to be the defining issue in decarbonising heat generation on the estate. Everything that can be done to reduce peak loads will help but it may still prove necessary to enhance the supply of grid power to the estate. This needs to be considered early in the scoping of low-carbon heat projects: it tends to be one of the defining issues in the design concept.

Transport. If the school has any integral transport it will need to be converted to electric vehicles. Charging points will also need to be installed.


Resolving issues within the existing buildings will inevitably be the most time-consuming and expensive part of the task, given that by 2050 (the UK’s overall net-zero target date) an estimated 80% of buildings in the UK will still be from the current building stock (i.e. not very energy-efficient). However, it is also vital that all new-builds are specified to high standards of energy efficiency and use low-carbon technologies for energy generation. It would be counter-productive for any new-builds in UK schools to be designed with fossil-fuel systems as their primary means of energy generation.

System Controls

Systems will increasingly need to be integrated so that they work to each other’s advantages. For example, solar PV arrays on site will not only provide power for functions such as lighting and IT: they will provide supplementary power for running the heat pumps. Spare power will be used to charge up EVs: but conversely, EVs will also function as power storage systems, which can push power back into circulation when journeys are not required. Time-of-Use tariffs will be in use on the school’s grid supply contracts, meaning that grid power is bought when at its cheapest, then stored in batteries (or the EVs) ready for use at peak-demand times; or the cheaper grid power is used to run the heat pumps, which in turn store heat ready for use later, so that the heat pumps do not need to be running when grid power is at its daily price peak.

System controls will increasingly be the key to operating a cost-effective and economical system. This is the main reason why a holistic approach to decarbonisation is required: without it, opportunities to save money or generate revenue could be overlooked.


The textbook approach is to tackle the energy efficiency first, before converting the heat generation from fossil-fuels to a low-carbon alternative. This makes obvious sense because it will reduce operating costs all the more quickly. However, there is a further reason: if the heat demand can be reduced then a smaller low-carbon heating system can be installed, thus reducing the capital outlay. This matters, because low-carbon heating technologies are relatively expensive compared to the fossil-fuel systems they are replacing.

However, schools tend to have complex estates, with multiple plantrooms and widely varying build standards. Resolving all the efficiency issues within the existing buildings will inevitably take many years, whilst some buildings will possibly never be that efficient. In this situation it may be necessary to compromise and run concurrent programmes to improve energy efficiency and at the same time begin the conversion to low-carbon heat generation. Under this approach, the new low-carbon plant would be sized to meet most of the demand, but not the current peaks, with some retained fossil-fuel plant operating as back-up. Over time, as the concurrent energy efficiency programme continued across the estate, energy usage would reduce and usage rates would become aligned with the capacity for low-carbon heat generation, meaning that the remaining fossil-fuel plant could then be phased out altogether.

Prudence with Projects

It is easy to waste money on complex retrofit conversion projects, especially for the heating systems. This work is equivalent in scale to any major new-build project and an iterative risk reduction process is essential. Careful scoping, planning, and project definition by a qualified 3rd-party will pay dividends. Likewise, it is essential to have independent external support to run the tendering and installation phases, first to secure the right contractor(s) for the right price, then to supervise their work. Recent experience in the Education Sector has shown that project costs can be reduced by as much as 25-30% by judicious and diligent project management.


There is much to be done, in reaching net-zero. If you would like further advice on any of the points raised in this article, or want to book an estate decarbonisation plan, please contact the author – Nigel Aylwin-Foster.