HOME ENERGY
Whole-House Retrofit Planner Ireland
Combine upgrade quotes, current One Stop Shop grant values and an editable energy-saving assumption into one retrofit budget and payback plan.
Updated 22 September 2026
YOUR ESTIMATE
At a glance
SCENARIO READOUT
Energy-cost scenario using the assumptions entered. Actual generation, consumption, tariffs, grants and building performance can differ.
See calculation method & assumptions ↓COMPARE SCENARIOS
Saved versus current
SEE THE SCENARIO
How the numbers develop
Enter your situation
Use figures that match your real quote, payslip, bill or plan where possible.
Stress-test it
Change the assumptions that matter most instead of relying on one perfect-looking result.
Read the context
Use the methodology, Irish rules and limitations below before acting on the estimate.
What this calculator is for
A whole-house retrofit is a sequence of interacting measures rather than a shopping list. This planner helps assemble costs, grants and estimated energy effects across insulation, heating, ventilation, windows, solar and related upgrades.
For the solar part of a home upgrade, start at the Compound Solar Hub. Compare solar installation quotes separately and avoid double-counting savings between building efficiency and electricity generation.
If a heat pump is part of the plan, read our Heat Pumps in Ireland 2026 guide first. It explains the €12,500 grant bundle, HLI/technical-assessment rules, radiator sizing, SCOP and the running-cost maths behind the calculator assumptions.
How to read the result
The cheapest measure is not always the first measure you should do, but fabric measures often influence the suitability and sizing of later heating upgrades. Focus on the post-grant cost, expected comfort/energy effect and the dependencies between measures.
Worked example
Improving insulation and airtightness can reduce heat demand before a heat pump is sized. Installing a heat pump first in a poorly performing home can lead to a system that must work harder and may require expensive distribution upgrades later.
Irish context
SEAI offers individual grants and a One Stop Shop route for complete home upgrades. One Stop Shop projects generally target a minimum B BER and can include project management, assessment and multiple grant-supported measures. Grant values and eligibility differ by property type.
What can change the answer
Home age, construction type, existing BER, heating system, moisture risk, ventilation, contractor quotes and grant eligibility all matter. Traditional pre-1940 buildings can require different fabric approaches.
Common mistakes to avoid
Do not chase a BER letter while ignoring moisture, ventilation or comfort. Do not start grant-funded works before required approval. Do not assume a grant makes a measure economical without comparing the net cost. And avoid replacing windows purely for payback when cheaper fabric measures have not been assessed.
Related Compound tools
Use the BER Energy Cost Calculator for energy-intensity context and the Solar PV Payback Calculator for the solar component.
Frequently asked questions
Is a One Stop Shop mandatory?
No. SEAI also provides individual-grant routes.
Should I insulate before installing a heat pump?
The whole-house design should consider fabric and heat demand before final heat-pump sizing.
Are grant values the same for every property?
No.
Does this replace a home energy assessment?
No.
Fabric, ventilation and heating need to work together
A deep retrofit can fail to deliver comfort if measures are chosen in isolation.
Adding insulation and airtightness reduces heat loss, but tighter buildings also need appropriate ventilation to control moisture and indoor air quality. Installing a heat pump in a home with high heat demand can require higher flow temperatures and may reduce efficiency unless the fabric and heat emitters are suitable.
This is why a whole-house assessment is more valuable than simply ranking grants by size.
For older or traditional buildings, moisture behaviour deserves particular attention. Materials and construction details that work well in a modern cavity-wall house may not be appropriate for a solid-wall heritage building.
A strong retrofit plan therefore asks three questions for every measure: what does it save, what does it enable, and what could it compromise? The cheapest sequence is not always the best sequence if later work has to undo earlier work.
Use contractor quotes and professional design advice for final decisions; the planner is there to organise the financial scenario.
Advanced mode: model the full current heat-pump support only when it applies
The standard heat-pump grant is not necessarily the entire support available in a qualifying 2026 project. SEAI’s current schedule can also include support for required central-heating-system upgrades and a €4,000 renewable-heating bonus in qualifying replacement cases.
Compound does not assume those conditional supports apply. Advanced mode exposes them as separate opt-in switches:
- up to €2,000 for qualifying central-heating-system upgrades in a house, or €1,000 for an apartment;
- the €4,000 renewable-heating bonus where SEAI’s qualifying replacement conditions are met.
The model caps these supports against the entered heat-pump-system cost so grants cannot make the modelled measure cost negative.
Advanced mode can also include the published One Stop Shop assessment grant and the home-type project-management grant, capped against the “other retrofit / professional costs” amount entered. These are financial scenario inputs, not an eligibility decision.
Why grant eligibility must stay separate from the arithmetic
A grant table can tell you the maximum published support; it cannot prove that your property, measure, contractor, technical design or timing meets all scheme conditions. One Stop Shop projects have route-specific eligibility and post-works requirements, and heat-pump supports depend on the qualifying project.
Use the toggles only where you have a reasonable basis to expect the support, then confirm the final package with the registered provider/SEAI before relying on it in a budget.
Sequence the building before sizing the heating system
A whole-house retrofit works best as a system. Reducing heat loss through insulation and airtightness can change the size of heating system the home needs. Installing a heat pump first and improving the fabric later can therefore produce a different design outcome from planning the package together.
SEAI explicitly notes that a home must be sufficiently well insulated for a heat pump to perform efficiently and provides for a technical assessment of heat loss in the heat-pump process.
The planner should therefore be used to compare packages, not merely to total a shopping list of independent measures.
Fabric, ventilation and moisture must be considered together
Insulation and airtightness can improve comfort and reduce heat loss, but tighter buildings also need appropriate ventilation. A retrofit plan that chases energy savings without considering ventilation, moisture and indoor-air quality is incomplete.
For major projects, use the calculator as the financial layer around a technically designed retrofit rather than as a substitute for building assessment.
Individual grants and One Stop Shop are different project routes
SEAI allows homeowners to pursue individual energy upgrades over time or use a registered One Stop Shop for a managed, deeper renovation.
A One Stop Shop can coordinate assessment, grant application, contractors and follow-up BER, with eligible grants deducted upfront from the cost. A staged individual-grant approach can suit households that want to spread work over a longer period or retain more direct project control.
The cheaper route on paper is not always the better route if project management, sequencing risk and financing differ.
Grant approval comes before works
SEAI grant rules can require approval before work starts and registered contractors for eligible measures. Do not sign a budget on the assumption that a grant will definitely be paid simply because the calculator shows an amount.
Treat every grant as conditional until the property’s eligibility, measure, contractor and application route have been confirmed.
Compare net cost and energy effect separately
A high grant percentage does not automatically make a measure the best investment. A lower-grant measure can have a stronger comfort or energy impact.
For each package, compare:
- gross project cost,
- eligible grant support,
- net household cost,
- estimated energy reduction,
- comfort/resilience benefits,
- and whether the measure enables later upgrades.
Use the BER Energy Cost Calculator to translate energy-intensity changes into indicative household energy use and the Solar Payback Calculator for PV-specific economics.
See SEAI’s individual grants, heat-pump grant guidance and One Stop Shop information.
Method and limitations
The planner combines the selected measures, entered costs and selected grant assumptions into a scenario. Base grants follow the implemented published schedule; conditional heat-pump and One Stop Shop service grants are included only when selected in Advanced mode. Grant amounts are capped by the entered cost pools. Energy savings are indicative and cannot reproduce a detailed DEAP assessment, grant approval or contractor design.
Useful sources
READ THE CONTEXT