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Calcimator

Net Zero Building Calculator

Analyze whether your building can achieve net-zero energy status by comparing annual consumption against on-site renewable generation.

Inputs

%

Results

Annual Consumption (kWh)

26,377

Annual Generation (kWh)11,300
Net Energy (kWh)-15,077
Renewable Offset (%)42.84%
Additional Solar Needed (kW)13.34
Annual Energy Cost ($)$3,429.07
Annual Savings ($)$1,469.05
Is Net ZeroNo
How to Use This Calculator
  1. Enter the Floor Area in sq ft and Energy Use Intensity (EUI) in kBtu/ft²/yr.
  2. Enter Solar PV Capacity in kW DC and average Peak Sun Hours per day for your location.
  3. Enter System Efficiency percentage and any Other Renewable energy in kBtu/yr.
  4. Review Annual Consumption vs Annual Generation and Renewable Offset percentage.
  5. Check Net Energy balance and Additional Solar Needed to reach net-zero if there is a generation shortfall.

How the result changes with Floor Area (sq ft)

Floor Area (sq ft)Annual Consumption (kWh)
100,0901,320,062
350,0654,616,918
650,0358,573,146
900,01011,870,003

What each input means

Floor Area (sq ft)
Total conditioned floor area of the building in square feet.
Energy Use Intensity (kBtu/ft²/yr)
Annual energy use per square foot. Typical: home 30-50, office 50-80, hospital 150-250.
Solar PV Capacity (kW DC)
Nameplate DC capacity of the rooftop or ground-mount solar array.
Peak Sun Hours / Day
Average daily peak sun hours for your location. US range: 3.5 (Seattle) to 6.5 (Phoenix).
System Efficiency (%)
Overall system efficiency accounting for inverter losses, wiring, soiling, and shading.
Other Renewable (kBtu/yr)
Annual energy from wind, geothermal, or other on-site renewable sources in kBtu.
Electricity Cost ($/kWh)
Average retail electricity cost per kWh for financial impact estimates.

What each result means

Annual Consumption (kWh)
Total annual energy consumption converted to kWh.
Annual Generation (kWh)
Total annual renewable energy generation in kWh.
Net Energy (kWh)
Generation minus consumption. Positive = net-zero achieved.
Renewable Offset (%)
Percentage of consumption offset by on-site renewables. 100%+ = net-zero.
Additional Solar Needed (kW)
Extra solar PV capacity required to reach net-zero.
Annual Energy Cost ($)
Estimated annual electricity cost without renewable offsets.
Annual Savings ($)
Estimated annual savings from on-site renewable generation.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Floor Area (sq ft) = 2000, Energy Use Intensity (kBtu/ft²/yr) = 45, Solar PV Capacity (kW DC) = 10, Peak Sun Hours / Day = 4.5 = 7 input(s) provided
  2. Calculate Annual Consumption
    Annual Consumption = annualConsumptionKbtu / 3.412
    26377 = 26377
  3. Calculate Annual Generation
    Annual Generation = totalGenerationKbtu / 3.412
    11300 = 11300
  4. Calculate Net Energy
    Net Energy = netEnergyKbtu / 3.412
    -15077 = -15077

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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