Homsy

Energy Savings Calculator

A heat pump saves about 50 per cent of a heating bill here, loft insulation 25, glazing 15, and LED lighting 10 per cent of the electricity. Enter your bills, pick upgrades, and the calculator scales every saving by the age of the house, then reports the annual figure, the payback in years, and the net position out to thirty.

1 Current Bills

Your current monthly energy costs.

€
€

2 Home Details

Helps us estimate baseline efficiency.

3 Upgrades to Consider

Select the upgrades you're considering.

How the savings are estimated

Each upgrade saves a percentage of the bill it touches, and the arithmetic is that percentage multiplied by your annual spend and then by an age multiplier for the house. The electricity upgrades: LED lighting 10 per cent, A-rated appliances 12, solar 35. The heating upgrades: a heat pump 50 per cent, loft insulation 25, wall insulation 20, glazing 15, a smart thermostat 10. A home charger is entered as electricity going up by 5 per cent, because it is a swap out of petrol rather than a saving. The age multiplier is 1.3 for a home built before 1980, 1.0 for 1980 to 2000, 0.8 for 2000 to 2015 and 0.6 for anything newer — an old house wastes more, so the same measure recovers more of it.

Install costs are scaled by floor area against a 100 square metre reference: a 1,500 euro loft insulation job on a 150 square metre home is quoted at 2,250. Payback is cost over annual saving, the ten-year net is ten years of saving minus the cost, and the projection bars are the same subtraction at 5, 10, 15, 20, 25 and 30 years. Nothing is discounted and no energy price rise is applied, so a thirty-year bar is today's saving repeated thirty times — read it as a comparison between measures, not as a forecast of money.

Every percentage, every reference cost and every carbon figure on this page is ours. They are the kind of round numbers a surveyor would recognise and they are not a quote, they carry no regional adjustment, and they are worst as absolutes and best as an ordering: LED lighting and a thermostat pay back in a couple of years, insulation in a few, solar and a heat pump over a decade or more. One interaction the sum deliberately does not model is that measures overlap — insulate first and a heat pump saves less than the number here, because the bill it is taking a percentage of has already fallen.

Every figure above was read out of the code that runs on this page. Where a number is our own judgement rather than a published one, the note says so and cites nothing. Method last checked 21 August 2026.

Why energy upgrades beat most home improvements

Heating and electricity are among the largest bills most households pay, and a draughty, poorly insulated home loses part of what it buys through the roof, walls and windows.

Energy upgrades can pay for themselves. Unlike a renovation, whose return depends on a future sale, an energy saving shows up on every bill. A €500 insulation upgrade that saves €150 per year pays for itself in just over 3 years, then keeps saving you money for decades.

The key is knowing which upgrades give you the best return for your specific situation. A well-insulated home benefits less from more insulation but might benefit greatly from solar panels. This calculator helps you prioritize based on your current bills and home characteristics.

Frequently Asked Questions

How accurate are the savings estimates?
They are rough. Each saving is a fixed percentage of our own, scaled by the age of the house, and your result will differ with your climate, energy prices, home construction and habits. Use the figures to compare upgrades with each other rather than as a quote.

Which upgrade has the best payback?
With the figures here, LED lighting and a smart thermostat usually pay back fastest, insulation next, and solar panels and heat pumps take a decade or more. Your own bills set the exact years, and the calculator sorts your choices by payback.

Does the calculator account for energy price increases?
No. The projections apply no price rise and no discounting: a 30-year bar is this year's saving repeated 30 times, minus the cost. If prices rise, real savings would be larger than shown; if they fall, smaller.

Can I combine multiple upgrades?
Yes. Select several upgrades and the calculator adds their savings together. It does not allow for overlap: insulate first and a heat pump will save less than shown, because the heating bill it works from has already fallen.

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