Ireland version
How it works
Estimate steady-state room heat loss from entered fabric properties, air exchange and a local outdoor design temperature.
This is the Ireland planning view, with monetary inputs and outputs in EUR. A currency label does not establish that a tax rate, construction price, coverage rule or legal limit has been verified locally. The inputs and limitations below describe the actual scope.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?unitSystem=Measurement systemChoice · Optional · Default: metric · Accepted values: imperial, metric
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?wallArea=Exposed opaque wall areaNumber · Required · Default: 50
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?wallU=Wall U-valueNumber · Required · Default: 0.3
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?roofArea=Exposed roof areaNumber · Required · Default: 40
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?roofU=Roof U-valueNumber · Required · Default: 0.2
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?windowArea=Window and external door areaNumber · Required · Default: 8
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?windowU=Window/door U-valueNumber · Required · Default: 1.4
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?floorArea=Exposed floor areaNumber · Required · Default: 40
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?floorU=Floor U-valueNumber · Required · Default: 0.25
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?volume=Heated internal volumeNumber · Required · Default: 100
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?airChanges=Air changes per hourNumber · Required · Default: 0.5
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?insideTemp=Indoor design temperatureNumber · Required · Default: 20
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?outsideTemp=Outdoor design temperatureNumber · Required · Default: -5
Outputs
3-
fabricLossFabric design heat lossNumber
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ventilationLossVentilation design heat lossNumber
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totalLossTotal screening heat lossNumber · Primary output
Formula
heat loss, W = Σ(area × U-value × temperature difference) + 0.33 × air changes × room volume × temperature difference.
Calculations retain numeric precision internally. Displayed values are rounded for readability. Quantities that must be purchased as whole units are rounded up only where the formula explicitly requires it.
Read the inputs before calculating
- Exposed opaque wall area: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Wall U-value: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Exposed roof area: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Roof U-value: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Window and external door area: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Window/door U-value: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Exposed floor area: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Floor U-value: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Heated internal volume: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Air changes per hour: Enter the quantity described by the label.
- Indoor design temperature: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
- Outdoor design temperature: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
Reproducible worked example
The following is a fictional arithmetic example, not a local quote, a verified claimant or a market forecast. Its values are included so the formula can be checked. The form does not automatically confirm any verification checkbox.
| Input | Example value |
|---|---|
| Exposed opaque wall area (m²) | 50 |
| Wall U-value (W/(m²·K)) | 0.3 |
| Exposed roof area (m²) | 40 |
| Roof U-value (W/(m²·K)) | 0.2 |
| Window and external door area (m²) | 8 |
| Window/door U-value (W/(m²·K)) | 1.4 |
| Exposed floor area (m²) | 40 |
| Floor U-value (W/(m²·K)) | 0.25 |
| Heated internal volume (m³) | 100 |
| Air changes per hour | 0.5 |
| Indoor design temperature (°C) | 20 |
| Outdoor design temperature (°C) | -5 |
| Output | Calculated result |
|---|---|
| Fabric design heat loss | 1.105 kW thermal |
| Ventilation design heat loss | 0.4125 kW thermal |
| Total screening heat loss | 1.5175 kW thermal |
Interpreting a changed assumption
Start with one complete scenario and change only one input when diagnosing a difference. Recheck units, the period of every rate, whether an amount is recurring or one-off, and whether a cost is already included elsewhere. A larger calculated benefit is not evidence that an assumption is more likely to occur.
Limitations
- Use net opaque wall area so windows are not double counted. Thermal bridges, ground-coupled transient effects, heat recovery and room-by-room distribution are not modeled. This is not Manual J, CSA F280 or a certified design.
Frequently asked questions
What does this Room Heat Loss result represent?
Estimate steady-state room heat loss from entered fabric properties, air exchange and a local outdoor design temperature. It applies the displayed formula to your inputs; it does not infer omitted facts.
Are the starting amounts verified Ireland prices or legal rules?
No. Numeric defaults are illustrative unless an input or dated reference explicitly identifies a researched component. Currency is EUR; local quotes, eligibility and unsupported rules must be entered and verified separately.
What must I check before relying on the result?
Check the input units, supplier or authority evidence, the stated model exclusions and the period used for costs. This arithmetic does not supply missing site-specific design or local legal rules.
Can I compare or share different assumptions?
Change one assumption at a time and use the browser-local project or share controls. A shared URL contains the encoded input values; do not include information you do not wish to disclose.
Sources and reference scope
- DOE energy-use arithmetic — retrieved 2026-09-24. Energy consumption versus power; not a local tariff or an approval of this implementation.
- PVWatts: site-specific solar estimation — retrieved 2026-09-24. External site-yield model. AskCalculators uses your entered yield; it does not call or reproduce PVWatts.
- DOE insulation overview — retrieved 2026-09-24. Insulation and thermal resistance concepts; not structural or code approval.
These references support only their stated scope. They are not evidence that every local rule or price needed by the master expansion has been loaded.