Energy Efficiency Calculators

Improving a home’s energy efficiency involves a sequence of decisions at different stages, and each decision is more financially sound when it is based on numbers rather than general guidance. Which improvements should come first for your property type and construction era? Does a heat pump make financial sense relative to a boiler replacement? What size solar battery is optimal once an EV is factored in? Is it worth improving the EPC before selling? These are the questions this suite of fifteen tools is designed to answer.

The tools are grouped by decision stage: start with the sequencer or affordability tools to understand priorities, use the specialist calculators to model the financial case for each improvement, and use the financing and property tools to assess timing and funding. All tools run in the browser and do not store or transmit any data you enter. All figures are illustrative estimates and should be treated as planning context rather than financial advice. For significant decisions such as a heat pump installation, a remortgage, or a property sale, professional advice from a qualified installer, mortgage broker, or estate agent is the right next step.

How These Tools Work Together

Each tool answers a specific question, but the questions are part of a broader decision sequence. Understanding how the tools connect helps you use them in the right order rather than in isolation.

The natural starting point for most households is the home energy upgrade sequencer, which takes your property type, construction era, current EPC, and fuel type and produces a ranked list of improvements ordered by financial return per pound spent. The sequencer applies dependency rules (insulation before a heat pump for BUS eligibility) and flags which improvements may be available free through ECO4 or the Great British Insulation Scheme. This gives you a shortlist of two or three priority improvements rather than an overwhelming list of everything that could theoretically be done.

Once you have a shortlist, use the specialist tools to model each priority in detail. If insulation is the top priority, the insulation savings calculator shows all applicable types for your property side by side with costs, grant eligibility, and the loan case for any net cost. If a heating system change is in the picture, the boiler vs heat pump calculator models the fifteen-year comparison in full. If solar is under consideration, the solar savings calculator, battery size calculator, and EV charging optimiser should be used together: the interaction between them produces a combined system picture that is more useful than the three tools run in isolation.

Having established which improvements make financial sense and at what cost, the financing tools model how to fund them efficiently. The energy efficiency loan payback calculator shows when the energy saving outweighs the loan interest for each improvement. The green mortgage EPC calculator shows whether completing EPC improvements before a remortgage unlocks a rate reduction that materially changes the financing picture. The retrofit timeline planner brings timing and financing together: enter your remortgage or sale date and the tools you have chosen, and it produces a phased schedule with dependency rules and timing risks shown against a visual calendar.

For households in a property transaction : buying, selling, or remortgaging: the property decision tools model the transaction-specific financial questions. The property running cost comparator is designed to be used during a property search, before an offer is made. The EPC before selling calculator is most useful three to six months before a planned listing date, when there is still time to complete improvement works and have a new EPC certificate issued. The remortgage timing calculator is best used four to six months before a fixed rate deal end, when the rate picture is clearer and there is still time to complete EPC improvements if the green mortgage angle justifies it.

Related Guides

Frequently Asked Questions

Are these tools free to use?

Yes. All fifteen tools on this page are free to use with no registration, account, or personal information required. All calculations are performed in your browser using the inputs you enter. Nothing is stored on Squared Money’s servers, and no data is transmitted when you use any of the calculators. The tools are funded by Squared Money’s introducer service for home improvement loans: if you choose to check loan eligibility through the “Check eligibility” button, you will be directed to a separate loan enquiry process where information is handled in accordance with Squared Money’s privacy policy.

The tools are designed to be used repeatedly with different inputs as you refine your improvement plans. There is no limit on usage and no obligation to proceed to a loan enquiry after using any tool. The purpose of the calculators is to help you make better-informed decisions about home energy improvements, whether or not you ultimately borrow to fund them.

How accurate are the figures in these calculators?

All figures are illustrative estimates based on UK average data. They are useful for planning and for identifying which options are worth pursuing in detail, but they are not precise forecasts of what any specific improvement will cost or save for any specific property. The main sources of variation from actual figures are property size (the calculators use size bands rather than exact square meterage), local installer rates (which vary significantly by region and demand), and actual energy usage (which depends on occupancy, heating preferences, and tariff).

For decisions that involve significant sums: a heat pump installation, a remortgage, a property sale: treat the calculator outputs as a starting point for conversations with professionals rather than as final figures. A professional energy assessment, a mortgage broker consultation, or an estate agent’s valuation will produce more accurate and specific numbers for your property and circumstances. The tools are designed to help you arrive at those conversations better prepared, with the right questions identified in advance.

Which tool should I start with if I am completely new to energy improvements?

The home energy upgrade sequencer is designed as the starting point for most users. It asks for your property type, construction era, current EPC rating, current fuel type, and a rough budget range, and produces a ranked list of improvements ordered by return on investment with dependency rules and grant eligibility flagged. This gives you a concrete priority list rather than an overwhelming menu of options. Most households find that two or three improvements account for the majority of the available energy and cost benefit, and the sequencer identifies which those are for your specific property profile.

If you are primarily concerned about the affordability of current energy bills rather than improvement planning, the energy affordability calculator is a better starting point. It focuses on the proportion of income going on energy costs, which improvements would reduce that proportion most, and what support schemes may be available for your situation. If you are a landlord rather than an owner-occupier, the MEES portfolio planner is the most relevant starting point: it gives the compliance picture across your portfolio before any improvement planning begins.

Can I use these tools to apply for a grant or loan directly?

No. These calculators are planning tools only. They do not connect to any grant scheme, lender, or application process. Grant applications for ECO4 and the Great British Insulation Scheme are made through energy suppliers or local authorities, not through this website. The Boiler Upgrade Scheme grant is applied for by the MCS-certified installer on your behalf as part of the installation process. For any of these schemes, the current eligibility criteria and application process are on gov.uk or through the Simple Energy Advice service at simpleenergyadvice.org.uk.

If you want to explore a home improvement loan to fund works that are not covered by grants, the “Check eligibility” button throughout this site connects to Squared Money’s loan enquiry service. Squared Money is an introducer: it matches enquiries to regulated lenders but does not lend directly, set rates, or make lending decisions. Checking eligibility does not affect your credit score and does not commit you to borrowing anything.

All calculators and tools on this page are for illustrative and planning purposes only and do not constitute financial, mortgage, energy, or property advice. Figures are based on UK average data and will differ from actual costs, savings, and outcomes for any specific property or situation. Grant eligibility indications are based on EPC rating only and do not account for income, benefit status, or other eligibility criteria. Always verify current grant eligibility through the relevant scheme administrator. Your home may be at risk if you do not keep up repayments on a secured loan.