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Room-by-Room Heat Loss Calculations for MCS Installers
Outsource the calculation. Keep the rest of the design in-house.
- Last updated: September 2026
- Heat Loss Hub · For Installers
You do not have to outsource the complete heat-pump design just because you need help with the room-by-room heat-loss calculation.
Heat Loss Hub can complete the calculation stage and return the design loads to your team. You can then carry those figures forward into your own emitter sizing, flow-temperature design, heat-pump selection, cylinder sizing, pipe sizing, hydraulic design and final system specification.
KEY TAKEAWAY
You send the property information. We calculate the heat loss. You carry the design forward.
GET IN TOUCH
Send us the property information and we’ll return clear, traceable room-by-room design loads.
Heat-Loss-Only Support for Installers
Some installers need a complete outsourced design service. Others already have the technical capability to complete most of the system design themselves and simply need additional resource at the heat-loss stage. Heat Loss Hub can support either model.
For heat-loss-only projects, we complete the room-by-room calculation and hand the results back to your team. This can suit:
- MCS installers without a dedicated internal designer
- Small businesses with irregular project volume
- Companies experiencing temporary design backlog
- Installers who prefer to complete emitter and equipment selection themselves
- Internal design teams that need additional calculation capacity
- Businesses that want a second route to design resource
You can use the service for one project, occasional projects, several projects at once or regular ongoing volume. There is no need to hand over more of the design than you want to.
Why Room-by-Room Heat Loss Matters
A heat-pump design needs more than one whole-house heat-loss figure. The calculation should show what each individual room requires. There are two important outputs.
Whole-Property Design Load
The overall design heat loss helps inform the required heat-pump capacity.
Individual Room Heat Losses
The room-by-room figures are used to assess whether each room can be heated properly at the intended operating temperatures. These figures then feed into radiator sizing, underfloor heating design, emitter assessment and design flow temperature.
KEY TAKEAWAY
The whole-house figure helps size the heat pump. The room figures tell you what each room actually needs.
What You Send Us
The quality of the calculation depends on the quality of the information supplied. Typical inputs include:
- Property address
- Floor plans where available
- Room dimensions
- Ceiling heights
- Window and door dimensions
- Wall construction
- Floor construction
- Roof or loft construction
- Insulation information
- Ventilation information
- Extension details
- Relevant photos
- Any known survey limitations
Where the project is based on drawings, we may also need construction specifications, window schedules, proposed floor build-ups, roof specifications and relevant architectural notes.
The important thing is that there is enough information to understand the thermal envelope of each room.
Explore: What Information Does a Heat Pump Designer Need From an Installer?
Existing Property vs New Build
The information route depends on the project.
Existing Properties
For retrofit projects, the calculation will normally rely on survey information gathered from the actual building. That may include measured room dimensions, existing windows and doors, construction type, insulation, extensions, loft condition, floor type and ventilation details.
Existing homes often contain alterations that are not reflected in old drawings or EPC records.
New Builds and Renovations
New-build or major renovation projects can often be calculated from suitable plans and specifications. Useful documents may include dimensioned architectural drawings, floor plans, elevations, sections, construction specifications, window schedules and proposed U-values.
The more complete the design information, the less site measurement may be required.
What We Calculate
The room-by-room calculation considers the relevant heat losses for each space. Depending on the property information available, this may include wall heat loss, window heat loss, door heat loss, floor heat loss, roof or ceiling heat loss, losses to unheated spaces, ventilation heat loss and relevant design temperatures.
For each room, the result is a calculated design heat loss. Those room values are then combined to produce the whole-property design load.
What You Receive
The purpose of the service is to give your own team a clear set of design figures that can be used in the next stages of the project. The returned information will typically include:
- Room-by-room heat-loss schedule
- Individual room design loads
- Whole-property design heat loss
- Internal design temperatures
- External design temperature
- Fabric heat losses
- Ventilation heat losses
- Relevant assumptions
- Notes on unresolved or unusual items
- Date and revision reference
The report should make it possible to understand where the figures came from.
KEY TAKEAWAY
The result should be usable by another competent designer without having to guess how the figures were produced.
What Is Not Included in a Heat-Loss-Only Service?
Heat-loss-only means exactly that. Unless separately agreed, it does not automatically include:
- Radiator sizing
- Emitter selection
- Design flow-temperature selection
- Heat-pump model selection
- Cylinder sizing
- Pipe sizing
- Hydraulic design
- System schematic
- Equipment schedule
- Full heat-pump design pack
You can keep those stages in-house. If you want Heat Loss Hub to take the project further, those services can be added separately.
Explore: Outsourced MCS Heat Pump Design
How the Calculation Fits Into Your Design Process
A typical design sequence might look like this:
Survey → Room-by-room heat loss → Emitter sizing → Design flow temperature → Heat-pump sizing and selection → Cylinder and hot-water design → Hydraulics and pipe sizing → Final system design
Heat Loss Hub can stop after the heat-loss stage. Your team then continues with the rest of the design. That keeps the service modular.
KEY TAKEAWAY
We do not need to take over the whole design to help with one part of it.
Can You Use Our Own Survey?
Yes. If your survey process already captures the information required for the calculation, you can send us your own project data. That may come from your own survey form, architectural drawings, site notes, photos, videos, existing software exports or customer-provided information.
The important point is completeness and clarity. If something critical is missing, we raise a query rather than silently fill the gap with an assumption.
KEY TAKEAWAY
Missing information should trigger a query, not an invisible assumption.
Can the Calculation Be Done From Plans?
Yes, where the plans and specifications contain enough technical information. Good plans may provide room dimensions, ceiling heights, window and door sizes, building layout, exposed surfaces, construction type and proposed fabric performance.
This can work particularly well for new builds, extensions, major renovations and properties with detailed architectural drawings.
However, not every set of plans contains enough information. Estate-agent plans, for example, can be useful for understanding layout but may not contain accurate dimensions, ceiling heights, window sizes, construction details or insulation specifications.
Where essential information is missing, further data will be required before the calculation can be completed reliably.
Can an EPC Be Used?
An EPC can provide useful background information. It may help with approximate property age, broad construction type, insulation history, glazing background and existing heating information.
However, an EPC is not normally enough on its own to produce a detailed room-by-room heat-loss calculation. The calculation still needs reliable information about individual room geometry, openings, exposed surfaces, construction and ventilation.
The EPC is supporting evidence rather than a replacement for the full design inputs.
How Assumptions Are Handled
Not every part of an existing building is always visible. Some information may need to be inferred from property age, construction type, drawings, EPC information, survey photographs or known building methods.
Where an assumption is required, it should be identifiable. The calculation should distinguish as far as practical between measured information, documented information, verified information and assumed information. Critical unknowns should be resolved where possible before the calculation is treated as final.
KEY TAKEAWAY
A calculated number is only as reliable as the information behind it.
Revisions and Changes
Heat-loss calculations are based on the property information supplied. If that information changes, the figures may also change. Examples include corrected room dimensions, different window sizes, updated glazing specification, different insulation, revised extension details, changed room layout or different roof construction.
Where a change materially affects the heat loss, the calculation should be revised.
KEY TAKEAWAY
If the property information changes, the calculation should change with it. Each revised issue should be clearly identifiable so your design team knows which figures are current.
One Project, Batch Work or Regular Volume
You can use Heat Loss Hub as much or as little as your workload requires. That could mean:
One Project
You have a difficult or time-consuming calculation and want to send just that job.
Occasional Support
Your own team normally completes heat loss, but you need help during busy periods.
Batch Work
Several surveys are ready and you want the calculation stage completed in one batch.
Regular Volume
Room-by-room heat loss becomes a routine outsourced stage in your workflow.
You keep control of the wider design process in every case.
White-Label Heat-Loss Calculations
Where required, heat-loss calculations can form part of a white-label workflow. That can allow the technical work to sit behind your own customer relationship. Depending on the agreed arrangement, your business remains customer-facing, Heat Loss Hub works behind the scenes, reports can follow the agreed branding approach, your customer remains your customer, and you decide how the calculation is presented within your wider design service.
This can be useful where you want additional technical capacity without changing the customer experience.
What Makes a Useful Heat-Loss Report?
A useful calculation should contain more than a final whole-house kW figure. It should make clear what rooms were calculated, what design temperatures were used, what building information was used, what assumptions were made, what each room loses, how the room figures relate to the overall property load and which revision is current.
That makes the calculation easier to review, continue designing from, revise later, hand to another competent designer and retain in the project record.
KEY TAKEAWAY
A useful report should show the basis of the numbers, not just the final kW figure.
Frequently Asked Questions
Yes. You can send us the property information, receive the room-by-room design loads and complete the rest of the system design yourself.
Room-by-room heat loss is fundamental to proper emitter design and allows the overall property load to be built from the individual spaces. A single whole-house estimate does not show what each room requires.
Typically room dimensions, ceiling heights, construction, windows and doors, insulation information, ventilation information, plans where available and relevant survey evidence. The exact information depends on the property.
Yes, provided they contain enough dimensional and construction information. Additional specifications may still be required.
Yes. If your survey contains the required information, there is no need to adopt a completely different process just to send the calculation to us.
An EPC can provide useful supporting information but is not normally enough on its own for a full room-by-room calculation.
We raise a query where the missing information could materially affect the result. The calculation continues once the required information is supplied or an appropriate assumption has been agreed and recorded.
Typically individual room heat losses, whole-property design load, design temperatures, fabric and ventilation losses, assumptions and revision information.
No, not automatically. Radiator or emitter sizing can be added separately if required.
No. The heat-loss-only service provides the design load. You can use that figure in your own equipment-selection process, or ask Heat Loss Hub to continue into full system design.
A white-label workflow can be agreed where required.
Yes. The service can support individual jobs, batch work or repeat project volume.
If the changed information could affect the calculated heat loss, the project should be revised so the design team is working from current figures.
Need the Heat-Loss Calculation Without Outsourcing the Whole Design?
Send us the property information. We calculate the room-by-room design loads. Your team takes those figures forward into the rest of the system design.
SUBMIT A PROJECT
Send us the property information and we’ll return clear, traceable room-by-room design loads.
Explore: Outsourced MCS Heat Pump Design
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