Base Capacity on the Home, Not Floor Area Alone

Collect home records

Gather plans, year and renovation records, insulation or window work, conditioned area and known air-sealing results without inventing missing values.

Map room comfort

Record room-by-room hot, cold, noise or airflow concerns by season and time rather than averaging them away.

Describe existing use

Collect equipment models, service records, fuel or electricity history and thermostat practices as context—not a shortcut calculation.

Document distribution

Map ducts, registers, returns, doors, stairways and possible indoor-unit zones plus known access constraints.

Require a load method

Ask how design outdoor conditions, envelope, ventilation, infiltration, internal gains and room loads are handled.

Keep the design record

Request inputs, assumptions, room or zone outputs, selected capacities, design conditions and limitations.

Build a room-by-room comfort record

For each room, note use, occupancy, exposure, window context, existing emitter or register, seasonal complaint and door position. Add envelope changes separately so the assessment can distinguish current conditions from planned improvements.

• Record hot and cold periods
• Include basement and additions
• Avoid choosing capacity from floor area

Reconcile design inputs

Ask the proposal to state outdoor and indoor design conditions, envelope assumptions, ventilation or infiltration treatment, internal loads and calculation method. Resolve mismatches between site observations, audit data and default assumptions before equipment selection.

• Keep the calculation report
• Flag assumed construction values
• Recalculate after envelope changes

Connect capacity to distribution

A calculated building load must still be matched to ducts, heads, airflow, zoning and room delivery. Require the assessment to explain design-condition output, part-load operation, defrost, backup and unresolved distribution work.

• Map every served room
• Identify airflow constraints
• State backup design role

Complete the house-to-selection brief

Combine room comfort observations, envelope and renovation facts, design-condition assumptions, load calculation, duct or head distribution evidence, ventilation context, electrical information and backup goals. Identify values that were measured, documented or assumed and attach the qualified reviewer’s method. Connect the selected equipment pairing to low-temperature output and room delivery, then list conditions that trigger recalculation. The brief should help every proposal use the same house evidence without presenting floor area, an online estimate, nominal equipment size or an incentive list as proof that capacity and comfort will be suitable.

• Map every served room
• Mark assumed envelope values
• Reference calculation revision
• Attach performance tables
• Name reassessment triggers