Renewable heating
Air source heat pumps
Property-led design, installation and support for air-to-water heat pumps across Surrey.
Explore service →Across Surrey
Heat loss and system design
Room-by-room evidence for sizing heat pumps, emitters and controls.
10+ yearsdomestic heating experience stated by NW Heating
Air + groundheat-pump installation, repair and maintenance
Whole homeheat loss, emitters, controls and hot water
Surrey20 locally focused service-area pages
Direct answer
What this service involves
A room-by-room heat-loss calculation estimates how much heat the property needs at a defined outdoor design condition. It informs heat-pump capacity, emitter sizes, flow temperature and whether fabric improvements should be considered.
When it may suit your home
A detailed heat-loss assessment is essential before a heat-pump installation and valuable when an existing low-temperature system is uncomfortable or expensive to run.
A clear route
How we approach heat loss and system design
- 01
Measure exposed areas and construction types
- 02
Record windows, doors, ventilation and design temperatures
- 03
Calculate room and whole-house heat losses
- 04
Compare emitter output at candidate flow temperatures
- 05
Turn the results into a practical system proposal
Clear answers
Heat loss and system design: frequently asked questions
Answers are shown in full so they remain useful and accessible. Property-specific decisions still require survey evidence.
Browse the full FAQ library →Is an EPC enough to size a heat pump?+
No. An EPC is useful context but is not a substitute for a detailed room-by-room design calculation.
Why does flow temperature matter?+
Lower flow temperatures generally help heat-pump efficiency, but emitters must still provide the required room output.
Should insulation come first?+
Cost-effective fabric improvements can reduce the design load, but priorities depend on the home, budget and disruption.
What information helps before a heat loss and system design visit?+
Share the property type, current heating fuel, recent energy use where available, comfort problems, planned building work and photographs of the existing equipment. This helps us identify the right survey or diagnostic visit.
How is heat loss and system design priced?+
A reliable price follows a defined scope. Equipment, access, diagnostic or heat-loss work, emitter and cylinder changes, electrical work, controls, commissioning and aftercare can all affect the quotation.
Related services for your next decision
Continue with the services most closely connected to heat loss and system design.
Renewable heating
Ground source heat pumps
Long-term ground-source heating designed around land, geology, heat demand and the home’s emitters.
Explore service →
Renewable heating
Underfloor heating
Low-temperature heat distribution for renovations, extensions and new homes.
Explore service →Bring us the real heating problem
Tell us what is working, what is not and what you hope to change. We’ll recommend the right next assessment.
Design evidence
What we check before recommending heat loss and system design
Renewable heating works best when the recommendation follows measured evidence. We look at the building fabric, room-by-room heat demand, the condition and output of radiators or floor circuits, water temperatures, pipe sizes, hot-water storage, controls, electrical supply, access and where equipment can be serviced safely. For a fault or maintenance visit, the same whole-system view helps separate a component problem from an operating or design symptom.
The proposal should state its assumptions, including the design outside temperature, intended flow temperature, expected emitter output, hot-water strategy and any enabling work. Where information is uncertain, we explain what must be measured or confirmed rather than hiding the uncertainty inside a product allowance.
Homeowner decisions
Questions worth resolving early
Think about the rooms that are difficult to heat, how the household uses hot water, acceptable disruption, future extensions, insulation plans and the space available for cylinders, controls or outdoor equipment. These details can change the sensible sequence of work and prevent avoidable alterations later.
Performance and running cost cannot be guaranteed from a product label. The useful comparison is a written system design with clear heat-demand and tariff assumptions. We can also explain where the Boiler Upgrade Scheme may apply, while keeping grant eligibility separate from the engineering decision.
- Clear scope and responsibilities
- Property-specific assumptions
- Commissioning and handover evidence
- Maintenance and fault-support route