Building Energy Input Form
Example Data Table
| Building Type | Floor Area | Electricity | Gas | Solar Offset | Target EUI |
|---|---|---|---|---|---|
| Office | 50,000 ft² | 720,000 kWh | 18,000 therms | 120,000 kWh | 45 kWh/ft² |
| School | 85,000 ft² | 900,000 kWh | 31,000 therms | 160,000 kWh | 40 kWh/ft² |
| Clinic | 35,000 ft² | 680,000 kWh | 15,500 therms | 70,000 kWh | 62 kWh/ft² |
Formula Used
Gas kWh: therms × 29.3001
Propane kWh: gallons × 26.80
Fuel oil kWh: gallons × 40.60
Net site energy: total purchased energy − onsite solar offset
Site EUI: net site energy ÷ floor area
Annual cost: energy quantity × utility rate, plus demand charges
Emissions: energy quantity × carbon factor
Source energy: energy quantity × source factor
Envelope UA: Σ(area × U-value)
Conduction heating: UA × HDD × 24 ÷ 3412.142 ÷ heating efficiency
Conduction cooling: UA × CDD × 24 ÷ 3412.142 ÷ cooling COP
Ventilation CFM: ACH × building volume ÷ 60
Lighting energy: lighting power density × area × hours ÷ 1000
How to Use This Calculator
Enter the annual utility data first. Add electricity, gas, propane, oil, district heating, district cooling, and solar offset values.
Next, enter rates and carbon factors. Use local utility bills when possible. Default factors are only starting values.
Add envelope areas, U-values, degree days, air changes, and building volume. These values help estimate physics-based heating and cooling loads.
Enter lighting density, equipment density, operating hours, occupants, target EUI, and planned savings. Press the calculate button.
The result appears above the form. Use CSV or PDF buttons to save the report.
Building Performance Energy Guide
Why Whole Building Energy Matters
Total building performance energy analysis connects utility use, physics, cost, carbon, and comfort. It helps owners see how a building uses energy during a full year. The method is useful for offices, schools, clinics, shops, warehouses, and mixed spaces. A good review does not look at electricity alone. It also converts fuels into comparable energy units.
Understanding Site Energy
Site energy is the energy used at the building. Electricity is already entered in kilowatt hours. Gas, propane, and fuel oil are converted into equivalent kilowatt hours. Solar production can reduce purchased energy. The calculator then divides net energy by floor area. This gives energy use intensity, also called EUI.
Using Physics Inputs
The envelope model uses area and U-value. A lower U-value means better insulation. Heating degree days estimate cold weather demand. Cooling degree days estimate hot weather demand. Air changes per hour estimate outdoor air entering the building. More leakage increases heating and cooling loads.
Cost and Carbon Review
Energy cost depends on utility rates and demand charges. Peak demand can be expensive, even when annual energy seems reasonable. Emissions depend on carbon factors. Electricity factors vary by grid. Fuel factors vary by fuel type. For planning, use local factors from your utility or energy authority.
Performance Comparison
The target EUI field lets you compare actual performance with a goal. A value above one hundred percent means the building uses more energy than the target. A lower value means better performance. Savings estimates show possible reductions in energy, cost, and emissions.
Better Decisions
Use this calculator before audits, retrofit studies, or budget planning. Try different insulation values, solar offsets, operating hours, and savings targets. Compare scenarios carefully. The result is an estimate, not a final engineering model. Still, it gives a strong first view of building energy behavior.
FAQs
What is total building performance energy?
It is the combined review of annual energy use, cost, emissions, peak demand, envelope loads, ventilation loads, and performance targets for a whole building.
What is EUI?
EUI means energy use intensity. It divides annual building energy by floor area. It helps compare buildings of different sizes.
Why convert gas into kWh?
Conversion places electricity and fuels on one common energy scale. This makes total site energy easier to compare.
Does solar reduce site energy?
Yes. The calculator subtracts onsite solar offset from total purchased energy. It does not allow net electricity to go below zero.
What does the UA value mean?
UA measures heat transfer through the building envelope. It combines surface area and U-value for walls, roof, windows, and floors.
Are default carbon factors final?
No. Defaults are sample values. Use local grid factors and accepted fuel factors for better reporting accuracy.
Why include peak demand?
Peak demand affects utility charges. A building can have moderate annual energy but still pay high charges during peak periods.
Can this replace an energy model?
No. It is a practical estimate. Detailed design should use professional simulation, measured data, and qualified engineering review.