Multiple-variable energy forecast calculator

Estimate energy from several measured drivers using fitted coefficients; each term must have energy units.

Units

E_{\text{pred}} = a \times \text{Production} + b \times \text{Floor area} + c \times \text{Degree days}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Worked example

Given

$a$ = 4,600 Btu/unit
$\text{Production}$ = 900 unit
$b$ = 240 Btu/ft²
$\text{Floor area}$ = 8,000 ft²
$c$ = 1,800 Btu/(°F·day)
$\text{Degree days}$ = 450 °F·day

E_{\text{pred}} = 4600 \times 900 + 240 \times 8000 + 1800 \times 450 = 6{,}870{,}000

Symbols and units

Symbol	Meaning	Unit
$E_{\text{pred}}$	predicted energy	Btu
$a$	production coefficient	Btu/unit
$\text{Production}$	production level	unit
$b$	area coefficient	Btu/ft²
$\text{Floor area}$	floor space	ft²
$c$	weather coefficient	Btu/(°F·day)
$\text{Degree days}$	weather measure	°F·day

Symbol	Meaning	Unit
$E_{\text{pred}}$	predicted energy	MJ
$a$	production coefficient	MJ/unit
$\text{Production}$	production level	unit
$b$	area coefficient	MJ/m²
$\text{Floor area}$	floor area	m²
$c$	weather coefficient	MJ/(K·day)
$\text{Degree days}$	weather measure	K·day

Related calculators

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.