1.3 Benefits of a Successful Retrofit

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 What is a robust retrofit and why would I want one?

By the end of this lesson, you will have learned…

  1. about the cost of not retrofitting
  2. the key benefits of a robust retrofit
  3. which benefits are most relevant for tenants, home owners, landlords and other groups
  4. the issues that a robust retrofit aims to avoid

1. The cost of not retrofitting

Let’s start by looking at some of the costs associated with energy-guzzling homes.


Can you list 5 or more disadvantages associated with an inefficient house?

Which of of these have financial implications and which are just “inconvenient”?

Below is a selection of costs and some specific examples.

Did your list cover all these points?

Were there any items on your list that are not included below?

1.1 Health and comfort

There are many potential health risks to living in a hard-to-heat building.

Example 1: There is evidence to suggest that heart attacks and strokes are significantly more likely to occur at indoor temperatures of 5-10°C than at 18-20°C. (Public Health England)

Example 2: Government statistics show that cold weather and overheating both lead to an increase in deaths or hospitalisation of the old, young or those with reduced mobility.

Example 3: Indoor air quality can affect our health in the short and long term, in a wide variety of ways.

Lessons 1.4 and 1.5 focus on the health and comfort of occupants in more detail.

1.2 Long term health of the building

A lack of maintenance can put a building at risk of deterioration. Leaving small problems untreated can lead to much larger and more costly issues in the future. Often, we are unaware of the full costs coming our way when we buy a house.

Example 1: where an issue such as damp exists, the previous owner(s) may have redecorated several times without rectifying the problem. The new owner comes in to find damaged plaster and decorates the room again. It is rare that the costs of successive redecorations are known and added up.

When retrofitting, it is essential to get fully up to date with maintenance. Likewise, if essential maintenance is needed, this can be a good time to include energy efficiency opportunities.

Retrofit can change the balance of a building and damage the long term health of the building if unsuitable approaches are taken. This effect can be exacerbated if there are already issues present in the building.

The importance of maintenance and appropriate retrofit approaches is covered in more detail later, particularly in Module 5.

1.3 High energy bills

The rising cost of energy bills is an issue for many households.

Living in a hard-to-heat home on a very low income can have far-reaching implications for some householders. Having to choose between paying the rent, buying food or heating the home can lead to spiralling financial problems, health problems or both.

Even for those who are not on low incomes, there can be a high cost and “hassle factor” associated with an inefficient home.

Example 1: There are plenty of homes where the occupants run the central heating but still need an electric fire to counter the draught around their feet. The same home may feel hot and dry with the heating on, but cools down rapidly as soon as the heating goes off. Energy bills are high, but comfort is less than ideal.

Example 2: It is common to find homes where dehumidifiers are used to control excessive levels of humidity. It is not cheap or convenient to buy and run a dehumidifier and empty it daily. While the dehumidifier removes excess moisture from the air, it does not remove chemicals that build up in the home or bring in fresh air from outside. A suitable ventilation system would require far less electricity to run, and would deliver better indoor air quality at the same time.

1.4 Looking at the national or global picture…

Energy security:

On a UK wide scale, there is a cost to saving energy through building fabric improvements and more efficient electrical appliances.

However, there is also a cost associated with increasing the national energy supply as well as storing and distributing that energy. So “not retrofitting” the nation’s homes has a cost attached.

Importing energy when demand cannot be met by national energy supplies leaves the UK vulnerable to price rises and geopolitics.

Climate change:

The costs of high carbon emissions globally are expected to increase into the future. Module 2 shows expected changes in the UK climate over the next 100 years.

A good retrofit can not only be “carbon light” (reducing carbon emissions from energy use and trying to minimise the embodied energy of the building itself)…..

It can also anticipate future changes to the climate by protecting the building/occupants from these changes. A future-proofed retrofit has the potential to save costs and provide other benefits in the long term.

Example 1: As hotter summers are anticipated to increase over the next 20 to 100 years, today’s retrofit can be designed to cope with very hot weather.

Example 2: Increased storminess is also expected in the UK, so in future buildings may be subjected to higher winds, and driving rain could become more severe or widespread.

Clearly all the costs mentioned above exist, even if it is difficult to accurately predict or calculate some of them.

If we could calculate and add up all the “costs of not retrofitting”, it would improve the business case for retrofit.

The case for retrofit is particularly strong if we consider the co-benefits, not just the direct benefits of a good retrofit.

For example, a diverse range of benefits is recognised in Figure ES.2 of the IEA’s report:

Recommended reading:Capturing the Multiple Benefits of Energy Efficiency“.

2. The key benefits of a robust retrofit

Good vs Bad Retrofit

Let’s start by contrasting what we want (a good, robust retrofit) with what we don’t want (a bad retrofit).


In your head or on paper, make your own list under the headings “A good retrofit…” and “A bad retrofit…”

E.g. A good retrofit…. does not suffer from overheating in summer

The table below highlights some key differences, but is not an exhaustive list:

Table with features of good and bad retrofit
Table with features of good and bad retrofit

A good retrofit should add to the value of the building for a number of reasons:

  • There are some home buyers already looking for homes that are comfortable and inexpensive to heat.
  • Retrofitting and maintenance can improve the appearance of the building. New or maintained soffits and fascias, for example, look better than those in need of repair. For anyone who doesn’t want to take on a lot of maintenance work, a well maintained and newly retrofitted building is appealing.
  • Some buildings are improved aesthetically during retrofit. For example, where an original facade looked tired or was in need of repair, the addition of external insulation and render or other finishes might be a big improvement.

3. Relevant benefits

The benefits of a successful retrofit depend to some extent on your perspective. Here, we consider the benefits for home owners, tenants, landlords and the government / wider society.

The list below summarises some of the multiple benefits of the ideal retrofit:

  • High levels of comfort
  • Healthy indoor environment
  • Low energy bills
  • A building that cools down slowly if the heating goes off (or the boiler breaks down)
  • Low risk, low maintenance, healthy building
  • A more attractive building
  • Low carbon emissions
  • Retrofit activity good for UK economy
  • Low heating needs in winter
  • Affordable cost of retrofit


Referring to the bullet point list above….

Which features would you expect to interest home owners (owner occupiers)?

Which would matter most to landlords?

Which are likely to be most important to tenants?

Which might impact the National Health Service?

Which might interest the UK government or be good for society in general?

What matters most to whom?

Most benefits on the list above will interest home owners. High levels of comfort and a pleasant indoor environment with good air quality are the key drivers for many home owners who decide to take on low energy retrofits. For some, getting the energy bills down and getting a lot of essential maintenance work out of the way are attractive aspects. A smart-looking retrofitted home with low energy bills will also be a positive selling point. Some will think of their reduced carbon emissions, and a retrofitted home as part of the legacy they leave for future generations.

Tenants will appreciate low bills and comfort. They may not be aware of the potential health benefits of a really good retrofit. However, they will be very aware of issues such as cold, damp and mould, especially if these have a negative impact on their health.

Landlords care about the cost of retrofit and ongoing maintenance. An attractive, well maintained building is more likely to attract new tenants. Lower bills and a healthy living environment are also important if it means they have happy tenants who can afford to pay the rent. Rent arrears are a big issue!

Health problems caused by overheating, fuel poverty, cold homes, poor air quality etc. all add to the burden on the National Health Service.

The government has carbon targets to achieve and a reduction in public health costs would undoubtedly be welcome. Retrofitting our way to a healthy economy would improve employment levels and tax revenues.

Energy security is a priority for governments – any government that fails to “keep the lights on” will not be popular with voters. Energy supplies can be stretched in winter when heating demand peaks. So having more homes that need less heating will reduce demand at the most critical time of year.

4. The issues that a robust retrofit aims to avoid

The diagram below illustrates some features of a poor retrofit and links them to issues for the occupants or the building itself.

Building issues in the centre lead to health issues (for people and buildings) in the next circle.

These, in turn, all have cost implications (listed beyond the outer circle). Poor retrofit can turn out to be a false economy.

Diagram showing costs and health impacts of building issues (Source: Tina Holt)
Diagram showing costs and health impacts of building issues. (Source: Tina Holt)

In some cases, the links between building issues and potential impacts are well understood. In other cases a link is suspected but may not be proven.

Example 1: Excess moisture held within the building fabric can lead to mould growth on timbers. Eventually, decay can lead to structural issues.

Example 2: Where “improvements” lead to mould growth behind internal insulation, or salts rising above tanking, etc., extra costs will be spent rectifying the situation.

(Moisture in the building fabric is covered in more detail in Module 5)

Example 3: When Relative Humidity is too high, it can lead to dust mite proliferation, which for some people leads to asthma attacks.

Example 4: Poor ventilation can lead to the build up of indoor chemical pollutants or mould spores, which can lead to respiratory problems in some people.

(Air quality is covered in more detail in Lesson 1.5)

Optional activity

Can you think of other examples?

Other issues that can result from a poor retrofit are:

Performance gaps (bad new build or retrofit)

Post-retrofit energy use is not always as low as was predicted.

Example: A heating system could end up being undersized if thermal improvements were not carried out to the intended standard. It will cost more to run and the building will be less comfortable.

This is covered in Module 4.

Anticipated pay back not met (due to bad retrofit)

Performance gaps generally lead to a higher energy bills than expected in the years after the retrofit.

Example: A home owner has borrowed money to complete the retrofit, and expects to pay that money back on the assumption that the energy bills are reduced. However, it turns out that the bills are only slightly reduced and this means there is less money available to repay the loan. For some people, this could lead to spiralling debt issues.


This lesson has introduced many of the disadvantages of not retrofitting, or of only achieving a poor quality retrofit.

It has highlighted some of the advantages of a successful, robust low energy retrofit.

And it has considered the benefits that are most relevant for different groups: occupants, building owners and the wider society.

Essential reading

Multiple Benefits of Energy Efficiency: from “hidden fuel” to “first fuel”

This more recent report (2019) has replaced the previous 2015 document cited here. Free registration with IEA may be required to access this: https://www.iea.org/reports/multiple-benefits-of-energy-efficiency#

Note: “In other literature, the multiple benefits of energy efficiency have been variously labelled “co-benefits”, “ancillary benefits” and “non-energy benefits” – terms often used interchangeably with “multiple benefits”. The IEA uses the term multiple benefits, which is broad enough to reflect the heterogeneous nature of outcomes of energy efficiency improvements and to avoid pre-emptive prioritisation of various benefits; different benefits will be of interest to different stakeholders.”


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