1. What is Building Heat Load?

The building heat load represents the amount of heating required to maintain comfortable indoor conditions. It's measured in British Thermal Units per hour (BTU/h) and is the sum of heat losses through the building envelope, ventilation, plus any internal heat gains.

2. Components of Heat Load

The total heat load consists of three main components:

Where:

• Envelope Load — Heat loss through walls, roof, windows, and floors (BTU/h)
• Internal Load — Heat generated by occupants, lighting, and equipment (BTU/h)
• Ventilation Load — Heat required to warm incoming ventilation air (BTU/h)

Explanation: The envelope load depends on the building's insulation and temperature difference between inside and outside. Ventilation load depends on air exchange rates and outdoor air temperature.

3. Importance of Heat Load Calculation

Details: Accurate heat load calculation is essential for proper HVAC system sizing, energy efficiency, and maintaining occupant comfort while minimizing energy costs.

4. Using the Calculator

Tips: Enter each component load in BTU/h. The calculator will sum them to provide the total heat load required for the building.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine the envelope load?
A: Envelope load is calculated using U-values of building materials, surface areas, and temperature difference (ΔT).

Q2: What's included in internal load?
A: Internal load includes heat from people (typically 400 BTU/h per person), lighting, appliances, and any process heat.

Q3: How is ventilation load calculated?
A: Ventilation load = 1.08 × CFM × ΔT, where CFM is airflow in cubic feet per minute and ΔT is temperature difference.

Q4: What's a typical heat load for a house?
A: Residential buildings typically range from 20,000-100,000 BTU/h depending on size, insulation, and climate.

Q5: Should I add a safety factor?
A: Professional calculations often include a 10-20% safety factor to account for estimation uncertainties.