Calculator Inputs
Example Data Table
| Input | Example | Unit | Reason |
|---|---|---|---|
| Conditioned floor area | 250 | m² | Used for load intensity. |
| Total conditioned volume | 750 | m³ | Used for infiltration load. |
| Wall area and U value | 180 and 0.35 | m², W/m²K | Used for transmission load. |
| Ventilation flow | 120 | L/s | Used for outside air load. |
| Safety factor | 10 | % | Allows design uncertainty. |
| Compliance limits | 95 and 125 | W/m² | Used for pass review. |
Formula Used
Envelope UA: UA = Σ(A × U)
Transmission load: Q = UA × ΔT
Infiltration load: Q = 0.33 × ACH × V × ΔT
Ventilation load: Q = 1.2 × L/s × ΔT
Heating load: Qh = max(0, envelope + infiltration + ventilation - internal gain credit) × safety × diversity
Cooling load: Qc = (envelope + infiltration + ventilation + sensible gains + solar gains + latent gains) × safety × diversity
Intensity: W/m² = final load in watts ÷ conditioned floor area
How To Use This Calculator
- Enter the conditioned area and volume.
- Add indoor set points and outdoor design temperatures.
- Enter each surface area and its U value.
- Add infiltration, ventilation, people, equipment, solar, and latent gains.
- Set the safety factor, diversity factor, and compliance limits.
- Enter installed heating and cooling capacity.
- Press calculate and read the status above the form.
- Download CSV or PDF for records.
Heating And Cooling Compliance Method
Heating and cooling compliance is a structured physics check. It compares the calculated building load with selected limits. It also checks plant capacity, safety margin, airflow, and equipment efficiency. The method is useful during concept design. It is also useful before submitting energy notes.
Core Calculation Logic
The calculation starts with temperature difference. Heating uses the indoor heating set point minus the winter outdoor design temperature. Cooling uses the summer outdoor design temperature minus the indoor cooling set point. These values drive heat transfer through walls, roofs, floors, and glazing. Each surface uses area and U value. A higher U value means faster heat flow.
Airflow And Gains
Air movement is the next part. Infiltration is estimated from air changes per hour. Ventilation is estimated from outside air flow. Both add heating and cooling load because outdoor air must be conditioned. Internal gains are then applied. People, equipment, lighting, and solar radiation increase cooling demand. A part of sensible internal gain may reduce heating demand.
Compliance Review
The calculator also applies a safety factor. This allows for rounding, operation changes, and uncertain site data. The result is shown in watts, kilowatts, and watts per square meter. The intensity value is important for compliance because it normalizes the load by floor area.
Compliance is not the same as comfort. A pass result means the submitted numbers meet the selected rules. It does not prove that every room will be comfortable. Room balance, duct sizing, humidity control, controls, and commissioning still matter. Use this tool as a method worksheet. Then compare the result with your local standard, code, or project brief.
Input Quality
Good input data improves the output. Measure envelope areas carefully. Use certified U values when available. Use realistic outdoor design temperatures. Enter ventilation from the design schedule. Enter equipment capacity from rated documents. Keep notes for every assumption.
Records And Exports
A strong submission should include formulas, inputs, results, and comments. It should also explain why each limit was selected. This calculator helps prepare that record. The CSV export is useful for spreadsheets. The PDF export is useful for design review. Always verify final compliance with a licensed professional or local authority.
When rules differ, update the limits and keep the same transparent calculation trail for review.
FAQs
What is heating compliance load?
It is the calculated winter load compared with a selected project or code limit. The result helps decide whether the heating design meets the selected requirement.
What is cooling compliance load?
It is the summer load caused by heat transfer, airflow, people, equipment, solar gain, and latent gain. The result is compared with the cooling limit.
Why does the calculator use U values?
U values measure heat flow through building fabric. Lower U values reduce heat transfer and usually improve heating and cooling performance.
What does ACH mean?
ACH means air changes per hour. It estimates how often outside air replaces indoor air through leakage and infiltration.
Why is ventilation included?
Ventilation brings outdoor air into the building. That air must be heated or cooled, so it can add a large load.
What is the safety factor?
The safety factor increases the calculated load. It allows for uncertain assumptions, future changes, and rounding in early design data.
What does a negative capacity margin mean?
A negative margin means the entered equipment capacity is smaller than the calculated requirement. The system may need review or resizing.
Can this replace local code review?
No. It is a calculation aid. Always compare the output with your local standard, project brief, and professional compliance process.