Whole House Plans: What They Are and Who Writes One

A whole house plan is a single staged document that sets out everything a particular property needs to reduce its energy use, in the order the measures should be carried out, with costs and expected savings attached. One established service describes its output as a tailored Whole House Plan that documents energy efficiency measures and outlines the costs and carbon savings, produced after a visit from a Retrofit Coordinator or an Energy Assessor who conducts an assessment of the home¹. Welsh Government guidance describes the whole house retrofit plan as containing impartial, scientific recommendations with detailed costings, architectural drawings and scheduling options, and as the most expensive assessment option, sometimes in the range of 750 pounds².

The reason for writing one at all is sequencing. The key, as one independent advice body puts it, is understanding what a home needs most, and doing things in an order so one improvement does not undermine the next³. A plan is therefore not a quotation and not a survey report: it is a route map over several years, covering fabric, heating and ventilation together. PAS 2035, the standard that governs funded domestic retrofit in the UK, promotes a whole-house approach specifically to reduce the risk of detrimental consequences for the health and comfort of residents, and requires the production of longer-term retrofit plans⁴.

Who writes it depends on the route. Under PAS 2035 the work is done by a qualified retrofit assessor and managed by a qualified Retrofit Coordinator⁵. Outside funded schemes, local one-stop-shop services, chartered surveyors and council-run tools produce equivalent documents: in Bridgend the Homewise service offers a tailored retrofit action plan with a personalised home energy action plan, an indicative EPC rating and a breakdown of the cost for any work and potential savings⁶; in a Cornwall village project, retrofit assessments and whole house plans were carried out by Paul Willingham of Two Counties Property Surveyors, with 45 completed⁷.

What a whole house plan actually contains

The contents vary with the provider, but the shape is consistent. At the top sits an assessment of the building as it stands. From that follows a list of measures, a proposed order, indicative costs and the expected outcome in energy, carbon or EPC terms. The Welsh Government description is the fullest available: impartial, scientific recommendations with detailed costings, architectural drawings and scheduling options². A local authority version, Bridgend's Homewise tool, produces a personalised home energy action plan, an indicative EPC rating and a breakdown of the cost for any work and potential savings⁶.

Scope matters as much as content. A deep whole-house retrofit aims to improve the building fabric, meaning walls, windows, floors and roofs, the heating system, and to install renewable energy where possible¹³. Ventilation sits alongside those, because sealing a house without addressing moisture is precisely the failure the sequencing rule exists to prevent³. Where the plan is written under the Welsh Optimised Retrofit Programme, it also sets out a route to net zero for each home⁵.

Quality control is built into the better services. Throughout the Cosy Homes Oxfordshire process, an independent Retrofit Coordinator keeps a check on the quality of the service and performs quality assessments, and homeowners gain access to a pool of trusted contractors vetted and rigorously assessed by the RetrofitWorks team¹.

Who is qualified to write one

PAS 2035 is the overarching UK retrofit standards framework¹⁴, developed by the British Standards Institute, and the standard calls for a Level 3 qualification in Retrofit Assessment for the assessor⁸. The project itself has to be managed by a qualified Retrofit Coordinator, which removes that burden from the householder⁹. Retrofit coordinators working under the framework are certified by TrustMark¹⁵, and under DESNZ schemes installations must comply with PAS 2035 with installers TrustMark registered or meeting equivalent requirements¹⁶. Within that structure, the retrofit designer is responsible for ensuring that selected products are appropriate and comply with Building Regulations¹⁶.

Traditional and historic properties carry extra requirements. For traditional or historic buildings, PAS 2035 mandates adherence to BS 7913: Guide to the Conservation of Historic Buildings; these projects are typically categorised as high-risk and require professionals to hold specialised qualifications, such as the ABBE Level 3 Award in Energy Efficiency and Retrofit of Traditional Buildings¹⁷. The standard recognises the unique nature of heritage buildings and encourages designers to develop solutions that respond to each building individually rather than adopting generic strategies¹⁸.

One structural weakness has been identified at official level. Retrofit assessors and retrofit coordinators can be appointed and contracted by the installer whose work they are assessing.

That is worth weighing when reading a plan produced by a firm that also intends to do the work. Further detail sits on retrofit assessors and retrofit coordinators and on what is included in a PAS 2035 retrofit assessment.

The figures: what a plan costs and what it commits you to

The plan is cheap relative to the work it describes, and that gap is the point of contention for most households. Citizens Advice notes plainly that the costs of this work are significant and for many homeowners there is currently limited financial support²⁰. The enabling cost figures deserve particular attention: across a sample of 14 whole house retrofit projects, actual enabling costs were far higher than estimated at the outset, at roughly 1,600 to 3,000 pounds per property, and enabling and repair works accounted for 26 per cent of total costs on average¹². Damp, failing roofs and electrical upgrades are discovered during assessment, not after it, which is one argument for a plan over a sequence of separate quotes.

Delivery timescales slip too. One service planned an eight-week customer journey between a customer registering and deciding which measures to go ahead with, and reported that the biggest barrier was the readiness of the supply chain for retrofit in its county to work in a coordinated way¹¹. Nationally, retrofitting the UK's homes will require at least 100,000 more trained workers¹⁰. See also what a whole-house retrofit costs in the UK.

What drives householder uptake

The UK Green Building Council commissioned in-depth consumer research to better understand how to encourage householders to take a whole-house retrofit approach rather than focusing on specific energy-saving measures, conducted via in-depth interviews in December 2020 with 10 homeowners across England who were either considering or had already undertaken efficiency measures, supported by EIT Climate-KIC²¹. The sample is small, so the findings are indicative rather than statistically representative.

The most useful finding for anyone weighing a plan: most householders are attracted to the idea of a whole-house plan once it is explained to them, especially the benefits of knowing upfront how to sequence measures and ensure forward compatibility²². Those contemplating more extensive works indicate they would willingly pay for the service²¹. A feeling of future proofing is also appealing²².

Two constraints recur. Householders' decisions are strongly affected by the length of time they expect to stay in their current home²². And householders surveyed categorised measures according to three stages of a whole-house retrofit journey, with a perception that benefits decline as costs increase²¹. That perception explains why loft insulation happens and external wall insulation often does not.

A far larger evidence base exists on attitudes generally: Citizens Advice worked from a nationally representative survey of over 10,000 homeowners on the barriers and motivators for energy efficiency and low-carbon upgrades²³. In Scotland, the Home Report is intended to give sellers an incentive to carry out repairs before marketing their properties²⁴, which is one of the few points in a property's life where retrofit decisions are naturally forced.

Provision across the four nations

Whole house plans are available across the UK, but the support around them is not evenly distributed. The clearest independent assessment is that the biggest gap in retrofit advice provision in Great Britain is in England, where only parts of the country have access to local services, meaning overall provision is inconsistent²⁶. A separate analysis records that a national retrofit advice service is needed in England only, because retrofit advice is already in place in Scotland, Wales and to some extent in Northern Ireland²⁷. The Climate Change Committee's comparison work states directly that England needs a comprehensive home energy retrofit scheme²⁸.

Funding also diverges. Specific retrofit grants outlined in the Warm Homes Plan will apply only to England²⁹. A parliamentary committee has identified a profound disparity between the public money invested in residential energy efficiency schemes per capita in England compared to the devolved nations³⁰.

Welsh policy also takes a broader view of who should be planning: holistic retrofit of all homes should be a priority, not just those rated EPC D to G³². Beyond national schemes, local and devolved schemes are available for households in some parts of the UK, varying by area and local authority³³. Nation-specific advice routes are covered on free home energy advice in England, Scotland, Wales and Northern Ireland.

The rules: PAS 2035, building regulations and planning

PAS 2035 was introduced in 2019 as a framework for best practice in the energy retrofit of domestic properties⁹. It covers the whole life cycle of a retrofit project, from initial engagement with a client, through assessment, design, installation and subsequent evaluation and monitoring³⁴, and incorporates the PAS 2030 installer standard³⁵. Current funded schemes reference PAS 2035:2023: ECO4 delivery guidance updated all references from PAS 2035:2019 to PAS 2035:2023³⁶. Regional pilots apply the same rule: under the West Midlands devolved retrofit pilot, all domestic retrofit installations must comply with appropriate safety and construction standards, including PAS 2035/2030:2023³⁷.

The standard also has a foothold in building regulations. PAS 2035 is already referenced in the current version of the Approved Document as a means to assess background ventilation in an existing dwelling, and that reference will be retained in the 2026 edition³⁸.

Planning is a separate question and a common trip hazard. Most retrofit measures do not require full planning permission, but some do, and this depends on the type of property and its location³⁹. For roof alterations, if the limits and conditions are not met, or permitted development rights have been removed in the area, then householder or full planning permission is required⁴⁰. Some councils publish permitted development checklists intended to help householders know which energy efficiency and renewable energy measures can be installed without the need to submit a planning application⁴¹.

Where the plans come from: services and community routes

The best-documented example is Cosy Homes Oxfordshire, a one-stop-shop home eco-retrofit service designed to support the homeowner from beginning to end of the retrofit journey¹. It launched in early 2019, is delivered in partnership by the Low Carbon Hub and RetrofitWorks, received two years of pilot funding from the then Department of Business, Energy and Industrial Strategy ending in March 2021, and now continues without grant funding, aiming to become a self-sustaining business for delivering whole house retrofit projects¹. The National Energy Foundation helped establish the scheme during its pilot phase¹. It uses a whole house, fabric first approach aimed at clients who are able to pay⁴². By March 2021, over 550 homeowners had registered, around 50 of them on a waiting list for an initial home assessment; an attempt to serve the rental sector was largely unsuccessful¹¹. More detail sits on Cosy Homes Oxfordshire.

Community organisations play a bridging role elsewhere. Carbon Co-op supported the delivery of an area-based retrofit scheme in South Manchester, acting as an intermediary between the professional parties involved and local residents⁴³. That model is covered on Carbon Co-op, and comparable services on regional retrofit advice services.

Funded and social routes differ again. Low-income households can receive fully funded upgrades⁴⁴. Salary sacrifice has been explored as a mechanism to let employees invest in a whole-house service covering assessment, retrofit planning, retrofit and systems installation, and repair and maintenance, repaid via gross salary contributions⁴⁵. Social landlord programmes commission plans at scale: Edinburgh's high-rise retrofit and upgrade programme uses the Passive House Planning Package as the energy modelling tool for each design commission's energy strategy⁴⁶.

What the evidence says about outcomes

Independent post-occupancy work offers a check on the promise. The Retrofit Revisit research examined the long-term performance of ten retrofitted housing projects across different locations and archetypes⁴⁷, nine of them houses and one a flat⁴⁸. Its headline finding is measured rather than triumphant: the retrofitted residences outperform the non-retrofitted housing stock overall⁴⁹. That is a real result on a very small sample, and the sample size is why it should not be read as a guarantee for any individual property.

The upper bound quoted in the literature is higher. Reductions in energy use and carbon emissions from deep whole-house retrofit can be as much as 80 per cent¹³. The same source sets out what the national task would involve: a programme to provide whole house retrofit for 9 million homes, at an average rate of one home every thirty-five seconds between now and 2050¹³. A parliamentary briefing puts the scope in one line: existing homes will all need to be retrofitted⁵⁰. Citizens Advice reaches the same conclusion from the household end, that to reach net zero almost all homes will require some level of retrofit²⁰.

Measuring what a plan delivered afterwards is a distinct exercise, covered on measuring savings after energy improvements.

What a whole house plan means for energy independence

Retrofit, at its simplest, is about improving a home's energy efficiency so it uses less energy to stay comfortable and healthy³, or in official planning terms, making changes to existing buildings to reduce energy use and therefore carbon emissions³⁹. The independence gain is straightforward: permanently reduce energy bills, improve energy security and cut carbon emissions²⁶. A house that needs less heat is less exposed to the price of whatever supplies that heat, and the reduction is permanent in a way no tariff is.

A plan contributes to that in a specific way, by making the sequence deliberate. Forward compatibility, knowing that insulation goes in before the heat pump is sized, that the ventilation strategy survives the airtightness work, is the difference between a home that reaches low demand and one that reaches a dead end partway. This is the argument set out in what order home energy improvements should be done in and a fabric first approach.

The dependencies that remain should be stated as plainly. A whole house plan does not disconnect a home from the grid; a deep retrofit may cut energy use and carbon by as much as 80 per cent¹³, which still leaves a fifth. Where a heat pump is installed, dependence shifts from gas to electricity and to grant policy: the Boiler Upgrade Scheme has provided grant funding towards heat pump installation⁴², and grant availability is a policy variable, not a fixture. The plan itself depends on a professional, a standard whose independence has been questioned at official level¹⁹, and often on a local service whose funding may have ended, as Cosy Homes Oxfordshire's pilot funding did in March 2021¹. Where a service closes, the plan remains, but the coordination around it does not.

Finally, the plan is a document, not a warmer house. It creates no obligation and delivers no saving until measures are installed, verified and, ideally, measured. Its value is that it converts a scattered set of possible purchases into a costed route with a known order, which is the practical starting point for planning a route to household energy independence and for anyone working through where to start.