Enter EMS Cooling Load Review Data
Use consistent design assumptions. This worksheet is a preliminary review tool. Confirm final selections with project requirements, manufacturer performance data, and qualified engineering judgment.
Sample EMS Review Inputs
| Input | Example | Why It Matters |
|---|---|---|
| Outdoor / indoor design temperature | 95°F / 75°F | Defines the temperature difference used for conductive and ventilation sensible loads. |
| Floor / roof area | 1,600 ft² / 1,600 ft² | Establishes the conditioned footprint and roof heat-transfer surface. |
| Window area / SHGC | 258 ft² / 0.38 | Estimates solar gain through exposed glazing. |
| Occupants | 18 people | Adds sensible heat and moisture released by people. |
| Ventilation / infiltration | 360 CFM / 64 CFM | Captures outdoor-air sensible and latent effects. |
| Allowance | 8% | Provides a controlled review margin after base loads. |
Calculation Method
Envelope conduction = U × Area × ΔTUsed for walls, glazing conduction, and roofs.
Window solar gain = Glass Area × SHGC × Solar Irradiance × Shading FactorUsed for simplified peak solar review of exterior glazing.
Ventilation sensible = 1.08 × Airflow (CFM) × ΔTUses the entered outdoor and indoor dry-bulb temperature difference.
Ventilation latent = 0.68 × Airflow (CFM) × Humidity Difference (grains/lb)Captures the moisture-related cooling demand from outdoor air.
Internal loads = People + Lighting Watts × 3.412 × Diversity + Equipment Watts × 3.412 × DiversitySeparates people sensible and latent gains before the final total.
Design load = (Sensible Load + Latent Load) × (1 + Allowance %)Capacity in refrigeration tons = Design Load ÷ 12,000.
Review the Cooling Estimate Step by Step
- Select the measurement system that matches your drawings and field data.
- Enter design temperatures, then add net enclosure areas and U-values.
- Use window area, SHGC, irradiance, and shading for the solar estimate.
- Enter peak occupants, lighting, equipment, and realistic diversity factors.
- Add ventilation, infiltration, and humidity difference from design psychrometric data.
- Choose a restrained allowance. Avoid repeating safety factors already included elsewhere.
- Calculate the result. Check the component table, airflow estimate, sensible heat ratio, and review flags.
- Download the CSV report or print the result for project records.
Why a Detailed Review Improves Cooling Decisions
An EMS cooling load review checks whether a proposed cooling estimate matches real building conditions. It connects measurements, schedules, and envelope data. Avoid simple oversizing. The goal is stable comfort, sensible capacity, moisture control, and useful operating data.
Start With the Design Condition
Choose realistic outdoor and indoor temperatures. A design temperature should reflect the project location and operating period. Indoor targets should match the building use. A server room, classroom, clinic, and workshop need different assumptions. Record the selected conditions inside the EMS review notes.
Review the Building Envelope
Walls, roofs, windows, and doors transfer heat. Their impact depends on area, U-value, and temperature difference. Window exposure adds solar gain. Shading reduces that gain. Enter measured areas where possible. Avoid using gross wall area when windows are included. This can double count the enclosure load.
Measure Internal Heat Sources
People, lighting, plug loads, and equipment create internal cooling demand. Their schedules matter. A room with high equipment load may peak after occupancy ends. Lighting controls can reduce load during daylight periods. Use diversity factors when every device does not operate together. Review EMS trend data to find realistic peak periods.
Include Outdoor Air and Moisture
Ventilation and infiltration can create major sensible and latent loads. Airflow raises sensible load when outdoor air is warmer. Moisture adds latent load when outdoor air contains more water vapor. Humidity differences should be checked carefully. Latent capacity is essential in humid climates and crowded rooms.
Use the Results for Review
The calculator separates sensible and latent components. It then adds an allowance for uncertainty. Compare the suggested capacity with available equipment. Check airflow, sensible heat ratio, and review flags. A very low sensible heat ratio may require improved dehumidification. An unusually large result may indicate incorrect areas, airflow, or schedule inputs.
Keep a Clear Audit Trail
Save the input values, assumptions, and final summary. Export the report for design review. Revisit the calculation after major envelope, occupancy, or equipment changes. This process supports better selections and clearer communication between estimators, engineers, contractors, and facility teams. It also makes EMS alarms easier to interpret after occupancy begins. Regular review reveals drift before comfort complaints, energy waste, or equipment stress become expensive operational problems during changing seasonal conditions.
EMS Cooling Load Calculator Questions
1. What does this EMS cooling load review calculate?
It estimates sensible and latent cooling demand from enclosure heat transfer, solar gain, occupants, lighting, equipment, outdoor ventilation, infiltration, and a selected design allowance.
2. Is this a final equipment selection tool?
No. Use it as a structured review worksheet. Final selection should consider local requirements, detailed load methods, duct design, equipment performance tables, controls, and qualified engineering judgment.
3. Why are sensible and latent loads separated?
Sensible load changes air temperature. Latent load removes moisture. Equipment must satisfy both requirements at the project design condition, especially in humid locations or densely occupied spaces.
4. What is the sensible heat ratio?
The sensible heat ratio is sensible load divided by total base load. A lower value indicates a greater moisture removal requirement and may affect equipment performance review.
5. How should I choose solar irradiance?
Use project climate data, orientation, glazing exposure, and the expected peak period. The simplified solar field is intended for review and should not replace detailed fenestration modeling.
6. Does the calculator include infiltration?
Yes. Enter estimated infiltration separately from required ventilation. Both airflow values contribute sensible and latent outdoor-air load in the calculation.
7. Why does the calculator use diversity factors?
Diversity factors recognize that lighting or equipment may not operate at full connected load together. Use EMS trends or operating schedules whenever available.
8. What allowance should be used?
Use a controlled allowance after verifying inputs. A small documented margin is often easier to defend than a large allowance that duplicates conservative assumptions elsewhere.
9. Can metric inputs be used?
Yes. Select Metric inputs. Areas, U-values, airflow, temperatures, solar irradiance, and person gains are converted internally before the final cooling result is displayed.
10. Why are there review flags?
Flags identify possible input conflicts or unusual results. They do not prove an error. Use them to revisit geometry, airflow, humidity data, schedules, and design assumptions.
11. Can the report be saved?
Yes. Download the CSV report after calculating. You can also use the Print / Save PDF button to create a project review record from the displayed summary.