How We Scope Projects

Guiding principles

Whole-house thinking

A home is a complex system and everything interacts. Even if the homeowner is focused on one area, we look at the whole picture first so that relevant problems, opportunities and interactions are surfaced.

Assess fabric first

Fabric directly affects active heating and cooling system design, and addressing heating and cooling demand with passive measures first is often better for comfort, cost and energy security in the long term. That said, not every project needs fabric measures - it depends on priorities, budget, tenure, and the current state of the home.

Expert-led, but for the homeowner

The homeowner's goals and priorities shape everything; they are what ultimately matters, and what will drive retrofit at scale. Our recommendations should align with those goals. This doesn't mean blindly accepting the measures a homeowner prefers, or simply offering a menu for them to choose from - it's our job to guide the homeowner to the right scope.

Informed by data and expertise

Where relevant and pragmatic, we use data from the home to model the impacts of improvements (savings, costs) and tailor our advice. This enables the homeowner to make better-informed decisions and guides our specifications. But not every factor can be quantified, and our professional judgement and experience is equally important.

Inputs we use

These are the data inputs we use to scope a project. Not all are available for every home - but the more we gather, the better our advice.

Understand the homeowner's project

The first step is understanding what the homeowner wants and what limits them. This shapes everything that follows.

Review their goals

Understand the goal(s) that have led them to energy efficiency upgrades. Common goals include:

• Improved comfort and health - typically leads to insulation, ventilation and active cooling measures

• Lower energy bills - typically leads to cheaper fabric measures like loft insulation and draught-proofing, plus solar panels, battery storage and smart tariffs

• Cutting carbon emissions - typically involves getting away from a gas or oil-based heating system and towards a heat pump

• Future-proofing the home - typically involves a bit of everything: controlling internal temperature, electrifying heating, generating and storing energy, and reducing overall energy demand

Review measures they are considering or excluding

• Which fabric elements are they open to upgrading?

• Are they interested in both heating and cooling measures, or just one type?

• Have they ruled anything out (and if so, why)?

Check for overlapping renovation plans

• Are they planning any structural works, like an extension or internal remodel?

  • These often overlap with energy efficiency works and can create timing opportunities (or constraints).

• How far along are they with any other plans (e.g. have they lined up an architect/builder, do they already have proposals/drawings)?

Review constraints and considerations

• Have they indicated a budget (for energy efficiency works and/or their overall renovation)?

• Are there limits on their tolerance for disruption?

• Do they have a soft or hard deadline on project completion?

• Are there any health or accessibility issues to consider?

Review current state of the home

Before assessing improvement opportunities, review where the home is losing and gaining heat, the extent of energy usage and costs, and any condition issues that need addressing.

Produce an overview that includes:

• Summary of property characteristics

• Absolute and relative heat loss estimate by building element

• Overheating risk estimate by room

• Known or suspected condition issues: e.g. damp and mould, failed insulation/ventilation, obvious heating system failures

Also include the following where applicable:

• Heat loss by room - include if a new heating system is under consideration

• Energy usage and emissions - include if the relevant inputs have been provided

  • Annual usage, costs and emissions

  • Per fuel (e.g. electricity, gas) and per usage type (heating, hot water, lighting)

Identify feasible improvements

By default, evaluate everything the homeowner is interested in or open to, as long as we cover it (see What We Cover). For every project, run a feasibility analysis and options evaluation for fabric measures and ventilation upgrades. Fabric inherently affects the design of active heating and cooling systems, and fabric issues and poor ventilation can lead to structural and health problems if they are not addressed.

Passive measures (fabric efficiency)

Assess each surface (unless explicitly excluded) for insulation or glazing opportunities:

• Would it benefit from new insulation/glazing? Is it uninsulated or single-glazed? Do other features sufficiently mitigate heat loss (e.g. party wall, heated basement)? If already insulated/double-glazed, is it working or suspected of failing? Are there any associated warranties or install records?

• For insulation, is there sufficient space? Is it feasible to reach the required depth for the target U-value? Would the installation be too complex to justify the benefit?

For each opportunity, determine:

• Are any specialist investigations needed before moving forward?

• Are any other works required before installation (e.g. due to cracks, damp or bad pointing)?

• Can it be accessed for installation?

• Do any planning requirements/restrictions or party wall issues apply?

Active measures (heating, cooling and ventilation)

Heating and cooling. Start by assessing opportunities to upgrade the current heating system, then assess opportunities to switch to a new system.

• Does the current heating system sufficiently address heat demand? Is there an active, working system? Are there working emitters in all rooms that require heat? Are those emitters sufficiently sized?

• Where emitters are insufficient, determine opportunities for independent upgrades: type (e.g. radiator, UFH), size and location. For wet systems, determine suitability of UFH as an alternative to radiator upgrades.

By default, assess feasibility for an A2W heat pump, but consider A2A if cooling measures are under consideration or the homeowner is explicitly interested in A2A systems. If the current system is not a wet system, focus on A2A feasibility only.

For heat pump feasibility, determine:

• Indicative siting for outdoor unit(s). Where is space available, and does it meet noise requirements?

• For A2W, where is space available for cylinder, volumiser etc.?

• Any planning requirements/restrictions or party wall issues

• Min/max system requirements depending on fabric: system sizing/capacity, whether a new hot water solution is needed, required emitter upgrades (type, size, quantity)

• For A2A and cooling specifically, the minimum number and location of indoor units to sufficiently address overheating risk

• BUS grant eligibility

Ventilation. Determine requirements for upgraded ventilation:

• Which rooms currently lack sufficient natural or mechanical ventilation?

• Where mechanical ventilation exists, is it working or failing?

• Do any potential fabric changes necessitate new ventilation?

• Are any other works required before installation? Any planning requirements?

Determine potential type and siting: trickle vent feasibility for windows (dependent on frame type), air brick feasibility for walls/subfloor void, and indicative locations for new or replacement mechanical ventilation (continuous or intermittent).

Generation and storage

Determine indicative siting for solar panels and battery storage:

• What is the maximum number of panels on the roof? Where could they be located/arranged? Where could a battery be located? Do any planning requirements apply?

• Estimated max solar generation capacity: max panels × per-panel capacity, with shade factor applied. What percentage of total energy demand could be served? What percentage would be self-consumed vs. exported (with and without a battery)?

• Appropriate battery storage capacity based on current energy consumption

• Any prerequisites: roof repairs or structural works before installation, whether the homeowner would need to switch energy provider or tariff

Compare options

Enter the feasible measures into an options evaluation tool, inputting measure classification (e.g. CWI), area/size and quantity. Review impacts including upfront cost (inc. available grants), impact on total heat loss, impact on overheating risk, impact on annual bills, EPC rating and CO2 emissions.

Break out measures where they can or should be installed independently, or wherever the configuration can vary (e.g. solid wall insulation per elevation, or core heat pump units and indoor emitters listed separately). Where the homeowner specifically wants to compare certain scenarios, use the standard tool live on the call to produce and compare each one.

Present a recommended, phased scope

Present one scenario as the explicit recommendation. Provide general commentary and rationale taking into account the homeowner's priorities, known constraints (budget, disruption, tenure, aesthetics), known home constraints (feasibility, other works, regulations), costs and savings from the options evaluation, and professional judgement on wider benefits, costs and risks.

Phasing

At minimum, split the scope into two phases: prioritise now vs. wait until later. By default, recommend passive measures first, unless there is a clear rationale for prioritising an active measure.

At the phase level, cover:

• Rationale for the phase

• Dependencies for the exact timing (e.g. walls stripped back for renovation, scaffolding up)

Item-level detail

For each item in the scope, include:

• Brief description

• Area/size/quantity and indicative location(s)

• All quantitative costs and impacts from the options evaluation tool

• Prerequisites (e.g. planning permission, specialist surveys, defect repairs)

• Any other notes or comments

Add preliminary works and repairs separately to the item list and populate a cost and description for them manually.

Also state any explicit exclusions to the recommended scope, with reasoning (e.g. the homeowner has made it clear they will not consider the measure).

Adjust scope based on homeowner feedback

If any scope questions or decisions remain after the pre-BuildPack scoping/planning call, send them over email as the next steps.

If the homeowner requests a different scope to the recommendation, generate a final scope output confirming what has been agreed, with all of the same information as the recommended scope.