# Room Heat Loss Calculator — Canada

> Estimate steady-state room heat loss from entered fabric properties, air exchange and a local outdoor design temperature. CAD planning view; stated limitations apply.

Page: https://askcalculators.com/ca/heat-loss/
Definition: https://askcalculators.com/ca/heat-loss/definition.json
JSON Schema: https://askcalculators.com/ca/heat-loss/schema.json
Version: 20.16.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/ca/heat-loss/?unitSystem=metric&wallArea=50&wallU=0.3&roofArea=40&roofU=0.2&windowArea=8&windowU=1.4&floorArea=40&floorU=0.25&volume=100&airChanges=0.5&insideTemp=20&outsideTemp=-5

## Inputs
- unitSystem: Measurement system; type=select; optional; default=metric; values=imperial|metric
- wallArea: Exposed opaque wall area; type=number; required; default=50; min=0; max=1000000000000
- wallU: Wall U-value; type=number; required; default=0.3; min=0.01; max=10
- roofArea: Exposed roof area; type=number; required; default=40; min=0; max=1000000000000
- roofU: Roof U-value; type=number; required; default=0.2; min=0.01; max=10
- windowArea: Window and external door area; type=number; required; default=8; min=0; max=1000000000000
- windowU: Window/door U-value; type=number; required; default=1.4; min=0.01; max=20
- floorArea: Exposed floor area; type=number; required; default=40; min=0; max=1000000000000
- floorU: Floor U-value; type=number; required; default=0.25; min=0.01; max=10
- volume: Heated internal volume; type=number; required; default=100; min=0; max=1000000000000
- airChanges: Air changes per hour; type=number; required; default=0.5; min=0; max=20
- insideTemp: Indoor design temperature; type=number; required; default=20; min=-10; max=40
- outsideTemp: Outdoor design temperature; type=number; required; default=-5; min=-80; max=40

## Outputs
- fabricLoss: Fabric design heat loss; format=number
- ventilationLoss: Ventilation design heat loss; format=number
- totalLoss: Total screening heat loss; format=number; primary

## Formula
heat loss, W = Σ(area × U-value × temperature difference) + 0.33 × air changes × room volume × temperature difference.

Inputs are converted to canonical units before evaluating this stated formula.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: Illustrative defaults are not local quotes or verified legal rules. Dated reference components and user-entered assumptions are explicitly distinguished. Professional review is pending.