Duct Sizing & Velocity Checker
Check duct velocity, equivalent diameter, airflow density, and noise-risk level.
Open ToolCooling Load Estimator
A planning-level HVAC calculator for estimating sensible and latent cooling load using area, occupancy, lighting, equipment, ventilation, envelope load, and project margin.
What is a cooling load estimator?
A cooling load estimator gives a first-pass HVAC cooling capacity from the main heat gain items that normally drive early design. It combines floor area, occupancy, lighting load, equipment load, ventilation allowance, envelope allowance, latent load, and design margin to estimate kW and refrigeration tons. Engineers use it when a project needs quick capacity planning before full heat-load software, detailed envelope data, or final schedules are available. It is useful for feasibility studies, concept design, tender checking, and comparing equipment sizes against expected room or building loads. The result is not a substitute for detailed HVAC design. Final cooling loads must account for climate data, orientation, glazing, diversity, infiltration, fresh air treatment, operating schedules, humidity, equipment performance, and approved design criteria. For best results, keep the entered units consistent, load the sample first, then adjust one assumption at a time so the result can be reviewed and explained.
Inputs
Forms are empty on load. Use sample data to preview the workflow or enter your own project values.
Learn more
Formula logic, use cases, assumptions, and limits for this tool.
How this tool helps
Use this for early HVAC planning, tender checks, and sanity checks before detailed heat-load software is used. It combines people, lighting, equipment, envelope, ventilation, latent allowance, and margin into a practical cooling estimate.
Assumptions and limits
This tool provides a planning-level result. It does not replace detailed engineering design, approved software, manufacturer data, authority requirements, or project specifications.
Typical use cases
- Early estimation and tender support.
- BOQ sanity checking and technical review.
- Site discussion before final engineering verification.
- Comparison of alternatives using consistent assumptions.
Result interpretation
Read the recommendation, warning, and confidence sections together. A result without warnings is still not an approval; it only means the entered values did not trigger built-in planning alerts.
Input definitions and typical values
These notes explain what each input means and which values usually produce a more reliable planning result.
Code / standard profile
Planning profile used for ventilation and HVAC defaults. GCC is hotter-climate planning, ASHRAE/CIBSE are general reference profiles. Options: GCC project planning, ASHRAE planning, CIBSE planning.
Floor area m2
Conditioned floor area. Small rooms are often 10-30 m2; apartments, shops, and offices can be much larger.
Room height m
Clear internal height. Typical rooms are 2.7-3.2 m; higher spaces need more air volume and distribution allowance.
Average outdoor temperature range
Usual outdoor temperature range for the location. Hot and extreme climates increase envelope load and power demand. Options: 25-32 C mild, 32-38 C warm, 38-44 C hot, 44 C+ extreme.
Floor / exposure level
Top floors, roof exposure, and corner rooms usually gain more heat than middle floors. Options: Middle floor, Ground floor, Top floor / roof exposed, Corner or highly exposed.
Occupants people
Expected people in the room. A quick planning value is about 0.13 kW sensible heat per person.
Lighting load W/m2
Lighting power density. LED offices are often 8-12 W/m2; older lighting can be 12-18 W/m2 or more.
Equipment load kW
Heat from computers, appliances, printers, kitchen/process loads, or other equipment. Use nameplate or estimated running load.
Outdoor air per person L/s/person
Fresh air rate per person. 8-10 L/s/person is a common planning range, subject to the selected standard and room use.
Envelope allowance W/m2
Allowance for walls, roof, glass, and solar gain. 60-90 W/m2 shaded, 90-140 W/m2 typical, 140-220 W/m2 hot/exposed/glazed.
Latent allowance %
Humidity and moisture allowance. 10-20% is common; humid climates or high outdoor air may need more.
Design margin %
Planning safety margin. 5-15% is common; too much margin can oversize equipment.
Practical verification checklist
- Confirm the selected standard profile is suitable for the project location and authority.
- Replace sample values with project drawings, schedules, equipment data, or measured site values.
- Review warnings, methodology, and PDF report before using the result outside early planning.
- Verify final decisions against official standards, manufacturer data, consultant specifications, and local approvals.
Related tools
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Open ToolCalculation methodology
Total kW = envelope + lighting + equipment + people + ventilation, with latent allowance and design margin. TR = kW / 3.517.
Inputs are treated as planning assumptions. The calculator shows warnings when entered values fall outside practical thresholds or selected standard-profile limits.
Version history
- v1.3.6-prelaunch: Added methodology, standard profile support, version notes, and direct PDF report download.
- v1.3.5: Calculator page added with sample data, warnings, and print-ready report layout.
Stage 2 roadmap: optional saved projects, dashboards, and shared calculation history without forcing login for free use.
Trust and verification
Every result includes assumptions, warning logic, and a downloadable report. Final engineering decisions still need qualified review, local authority approval, manufacturer data, and project specifications.
Worked example
Use the sample data button to load a realistic scenario, then download the PDF report to review inputs, results, methodology, warnings, and disclaimers in one place.