Home Retrofit Investment Calculator
- Calculator
- How-to
- About
How much should the UK Government invest to make upgrading the nation’s homes affordable and attractive?
Working with industry experts and academics, the UK Green Building Council has a created this calculator to open the books so you can ‘play’ Chancellor and Secretary of State.
Use the calculator to work out, as Chancellor, how much you would invest over what time frame. Who would you prioritise – people living social housing or privately owned homes? Fuel-poor residents or asset-rich owner occupiers? Which retrofit measures would you prioritise? How will your choices impact on energy bills, returns to the Treasury, public health, and climate emissions? As Secretary of State, what policies and regulations would you introduce to encourage private investment and shift markets?
The calculator has been developed to allow an evidence-based debate on the magnitude of investment and policies needed and to help us all assess policy decisions and priorities.
Quick start scenario
Select from one of four quick start template scenarios to pre-populate the calculator. Each quick start scenarios provides a different starting point: only focusing on energy efficiency, only low carbon heating, a combination of energy efficiency and low carbon heating, all values zeroed. There is also the option to upload a scenario you have previously saved (on your computer) or received from others.
Using these quick start scenarios you can then make your own adjustments and save these as appropriate. Details are here [4]
For each retrofit measure, you can use the sliders to adjust your level of ambition i.e. the percentage of suitable roofs or walls that you think should have solar panels or insulation. For example, if you select 100% for cavity wall insulation, then all homes with unfilled cavity walls that are suitable will be filled. More details here [1].
Financial support
You can amend the percentage % of government funding within each category and sub category to target the funding at specific household types, tenure types, and socio-economic groups as appropriate. Set to 0% for no government funding. Eg Private Rented, Fuel Poor = 60% reflecting a government grant of 60% of the value of the measures.
The ‘type’ of grant is not considered, simply the proportion of the cost of the retrofit measures selected. The grant could be a householder voucher, a contractor subsidy, a subsidised interest rate etc. In the case of the later, a zero interest loan over 10 years may be equivalent to a 30% ‘grant’ and reflected in the calculator as 30% government funding.
Duration
Set/update the duration of the funding and the overall delivery. Eg measures funded for the first 10 years with all completed in 20 years, meaning the last 10 years have no government support, just policies encouraging take up.
If different packages of measures need different durations such as: energy efficiency measures over one period, say 10 years, and low carbon heating over another, say 25 years, then it is necessary to create two separate scenarios and combine the outputs manually.
Complementary policies
Use the free text ‘complementary policies’ box to list the policies being assumed to encourage the co-investment from the homeowners, private or social landlords.
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- Rental (private)
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Other policy costs (£bn)
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Geography
Select the specific nations or select all for the UK. Note, in this version, Northern Ireland is not able to be selected on its own as the data used is not sufficiently representative.
Percentage cost reduction profile
Set a cost reduction profile to be applied to measure costs. This allows you to anticipate a reduction in the cost of installing measures due to the scale of activity and increases in manufacturing efficiency. The final value at year 5 is assumed going forwards. Set a negative % for a cost increase.
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Energy cost assumptions
Set cost assumptions applied within the model. The default energy costs are the January 2024 Energy Price Cap with an allowance of £0.044 deducted from the electricity tariff to represent removal of the social levys. These prices have been maintained throughout the period. Overtype to change these energy price assumptions.
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Export scenario
Add some final comments to contextualise your scenario and then download your parameters. These can be loaded back into the the Calculator in a future session to allow you to pick up where you left off.
