A Simple Guide to Deciding What to Improve First
Improving the energy efficiency of your home can save energy, reduce bills and make your home more comfortable.
However, knowing where to start is not always easy.
You may be told to install insulation, replace your windows, buy a new boiler, fit a heat pump or add solar panels.
Yet every home is different.
A measure that makes sense for one property may offer poor value in another. Likewise, spending thousands of pounds on new technology may achieve little if a simpler problem has been overlooked.
So, before buying anything, understand your home.
Understand → Investigate → Prioritise → Cost → Improve → Measure
This approach helps you spend money where it is most likely to make a difference.
Start With the Home You Have
Before thinking about improvements, look at how your home performs now.
Ask yourself:
- Which rooms are difficult to heat?
- Where do you feel draughts?
- Are some rooms much colder than others?
- Is there condensation or damp?
- How much energy do you use?
- What type of heating do you have?
- How well can you control it?
- What insulation is already present?
- Are windows and doors in good condition?
You may already know some of the answers.
Others may need further investigation.
The aim is not to find something to buy.
Instead, it is to understand what needs improving.
Start With Problems, Not Products
Energy efficiency is often marketed through products.
You may see advertisements for:
- New windows
- Boilers
- Heat pumps
- Solar panels
- Insulation
- Heating controls
- Smart technology
However, a product should solve a problem.
So, reverse the process.
Instead of asking:
“Should I buy new windows?”
ask:
“Where is my home losing heat, and why?”
Instead of:
“Should I install a heat pump?”
ask:
“What heating system would suit this property?”
This small change in thinking can prevent expensive mistakes.
Deal With Repairs First
A home should be in suitable condition before major energy-efficiency work begins.
For example, investigate problems such as:
- Roof leaks
- Penetrating damp
- Plumbing leaks
- Damaged gutters
- Failed seals
- Defective windows
- Poorly fitting doors
- Heating faults
Insulation will not repair a leaking roof.
Likewise, replacing a heating system will not solve a badly draughty external door.
Therefore:
Repair before you improve where the repair affects the improvement.
This also makes it easier to judge what energy-efficiency work is genuinely needed.
Understand Where Your Energy Goes
Your bills can provide useful clues.
Look at how much:
- Gas
- Electricity
- Oil
- LPG
- Other heating fuel
you use over the year.
If you have several years of bills, compare them.
This can help you understand seasonal patterns.
For example, a large increase in gas use during winter is expected in a gas-heated home.
However, unusually high summer gas use may encourage you to look more closely at hot water.
Likewise, high electricity use in an electrically heated property may be mainly caused by heating rather than appliances.
Therefore, look at the whole energy picture before concentrating on small savings.
Use kWh, Not Just Pounds
Your energy bill is affected by both consumption and price.
Therefore, comparing bills only in pounds can sometimes be misleading.
Imagine your bill rises from £1,500 to £1,800.
You might assume that you used more energy.
However, the increase could be caused by a higher tariff.
So, when assessing your home’s performance, look at the amount of energy used in:
kilowatt-hours — kWh
This gives you a better measure of actual consumption.
You can then consider the price separately.
Find the Biggest Opportunities
Not every improvement deserves equal attention.
For many homes, heating and hot water account for a large share of energy use.
Therefore, reducing unnecessary heat loss or improving heating control may matter more than worrying about a few watts of standby electricity.
In another property, however, electric heating or hot water may dominate the bill.
The important thing is to identify the larger opportunities first.
Don’t spend hours chasing pennies while ignoring pounds.
Look at the Building Fabric
The building fabric includes the parts of your home that separate the heated inside from the outside or from unheated spaces.
This includes:
- Roof
- Walls
- Floors
- Windows
- External doors
Heat can move through all of these.
Air can also move through unwanted gaps.
Therefore, consider both:
Heat loss through materials
and
Heat loss through uncontrolled air movement
They are related, but they are not the same problem.
Learn more about Insulation and Heat Loss →
Look for Draughts
Draughts can make a room feel uncomfortable even when the heating is running.
Common places include:
- Window frames
- External doors
- Floorboards
- Pipe penetrations
- Loft hatches
Some can be inexpensive to correct.
However, not every opening should be sealed.
Homes also need controlled ventilation to manage moisture and indoor air quality.
Therefore:
Stop unwanted draughts. Protect necessary ventilation.
Learn more about Draught Proofing and Ventilation →
Don’t Assume Windows Need Replacing
Cold areas around windows often lead people to think they need complete replacement.
Sometimes they do.
However, the problem may instead be:
- Worn seals
- Poor adjustment
- Damaged hinges
- A failed glazing unit
- A gap around the frame
Therefore, inspect and repair where practical before replacing a sound window.
The same principle applies to external doors.
Adjustment → Repair → Improvement → Replacement
Learn more about Windows, Doors and Floors →
Use Your EPC
Your Energy Performance Certificate can provide useful information about your property.
It may identify:
- Insulation
- Heating
- Hot water
- Windows
- Potential improvements
However, an EPC should be treated as a starting point.
It uses an assessment method and standard assumptions. It does not know exactly how your household uses energy.
Likewise, a recommendation on the EPC does not automatically mean that improvement should be your next purchase.
Instead:
Use your EPC as a guide, not a shopping list.
Learn more about Understanding Your EPC →
Check Whether Your EPC Is Still Accurate
An EPC can remain valid for several years.
During that time, the property may have changed.
For example, you may have installed:
- A new boiler
- Additional insulation
- New windows
- Solar panels
- Different heating controls
Therefore, compare the certificate with the home as it is today.
If something has changed, take that into account when planning further improvements.
Think of Your Home as a System
One improvement can affect another part of the property.
For example, reducing uncontrolled air leakage can change how the home is ventilated.
Adding insulation can change surface temperatures.
Installing a different heating system can change radiator or emitter requirements.
Adding solar panels may become more valuable if you later use more electricity for an electric vehicle or heat pump.
Therefore:
Improve the home as a system, not as a collection of products.
This is particularly important when planning several improvements over a number of years.
There Is No Universal Order
You may hear advice such as:
“Always insulate first.”
That can sometimes be sensible.
However, it should not become an absolute rule.
Imagine a home with a failing heating system.
The owner may need to replace the heating before they can afford major insulation work.
Alternatively, imagine a roof is already being replaced.
That may create an ideal opportunity to improve roof insulation at the same time.
Likewise, someone replacing a damaged floor may have a rare opportunity to consider floor insulation.
So, the right order depends on:
- The building
- Its condition
- Your budget
- Existing systems
- Planned work
- Your needs
- Practical opportunities
A plan should fit the property rather than force the property to fit a standard plan.
Start With Low-Cost Improvements
Some useful improvements cost relatively little.
Depending on the property, these might include:
- Adjusting heating schedules
- Using heating controls properly
- Repairing simple draughts
- Replacing damaged seals
- Adjusting windows or doors
- Improving hot-water controls
- Using appliances more efficiently
These changes may not transform the EPC rating.
However, they can still reduce waste or improve comfort.
They also give you time to understand the property before making larger investments.
But Don’t Assume Cheapest Means Best
A low-cost measure can offer excellent value.
However, price alone should not determine the order.
Suppose a cheap improvement saves very little, while a more expensive measure solves a serious comfort problem and reduces substantial heat loss.
The more expensive improvement may still be the better priority.
Therefore, consider:
Cost + Saving + Comfort + Need
rather than cost alone.
Separate Energy Saving From Financial Saving
These two ideas are connected, but they are not identical.
An improvement may reduce energy consumption substantially.
However, whether it saves enough money to justify its cost depends on:
- Installation price
- Energy price
- Maintenance
- Lifespan
- Actual use
For example, an improvement costing £5,000 and saving £200 a year has a very different financial case from one costing £500 and saving the same amount.
Therefore, calculate the numbers where possible.
Simple Payback
A basic payback calculation is:
Installation cost ÷ annual saving = simple payback period
For example:
An improvement costs:
£1,200
Estimated annual saving:
£150
Then:
£1,200 ÷ £150 = 8 years
The simple payback is therefore around:
8 years
This can be useful when comparing options.
However, it is only one part of the decision.
Why Payback Isn’t Everything
Some improvements provide benefits that are difficult to express in pounds.
These may include:
- Warmer rooms
- Fewer draughts
- Better temperature control
- Reduced condensation risk
- Lower carbon emissions
- Reduced outside noise
- Improved property condition
Likewise, an improvement may be worth doing because another part of the building already needs work.
For example, if a floor must be lifted anyway, adding suitable insulation at that point may be much easier than doing it separately later.
Therefore, simple payback should guide decisions rather than control every decision.
Be Careful With Claimed Savings
You may see claims such as:
“Save £500 a year.”
Ask what that figure is based on.
Savings may depend on:
- Property size
- Existing insulation
- Heating system
- Energy price
- Indoor temperature
- Occupancy
- Installation quality
A saving achieved in one property may not be repeated in another.
So, when comparing improvements, look for estimates that relate as closely as possible to your property and your energy use.
Consider the Life of the Improvement
An improvement that lasts for decades should not always be judged in the same way as a product with a shorter life.
For example, suitable building insulation may remain useful for many years.
Other equipment may eventually need:
- Servicing
- Repair
- Component replacement
- Complete replacement
Therefore, consider both the initial cost and what happens later.
Ask:
How long should this improvement last?
and:
What will it cost to maintain?
Think About Planned Work
One of the best times to improve energy efficiency can be when related work is already happening.
For example:
Replacing a roof?
Consider whether roof insulation should be improved at the same time.
Lifting floors?
Investigate whether suitable floor insulation can be included.
Replacing windows?
Think about ventilation and surrounding seals.
Renovating a room?
Consider heating controls, insulation and draughts before everything is finished.
Replacing a heating system?
Think about the home’s future heating needs rather than simply installing an identical replacement.
Planning improvements together can reduce disruption and sometimes reduce cost.
Heating Deserves Its Own Plan
Changing the heating system can be one of the largest energy decisions you make.
Before changing it, understand:
- Current heat demand
- Existing heating system
- Radiators or emitters
- Hot-water requirements
- Controls
- Insulation
- Available fuels
- Electricity supply where relevant
- Future plans
For example, moving from a gas boiler to a heat pump is not simply a matter of swapping one box for another.
The heating system needs to work as a whole.
Likewise, electric storage heating, direct electric heating and other systems have their own operating requirements.
Explore Heating & Hot Water →
Think About Future Electricity Use
Your electricity needs may change.
For example, you might later install:
- A heat pump
- Electric vehicle charger
- Solar panels
- Battery storage
- Electric hot water
- Additional electric heating
Therefore, consider future plans when making major decisions today.
This can help avoid paying for work twice.
It can also help you understand whether technologies such as solar PV may become more useful to you in future.
Renewable Technology Should Not Be the First Question
Solar panels and other renewable technologies can be valuable.
However, the first question should not simply be:
“Can I fit solar panels?”
Instead, ask:
- How much electricity do I use?
- When do I use it?
- Is the property suitable?
- What might change in future?
- What will the system generate?
- How much might I use myself?
- What will it cost?
- What maintenance is involved?
The technology should fit your home and your needs.
Again, start with the problem and the opportunity rather than the product.
Get Suitable Advice for Major Work
Some improvements are straightforward.
Others require much more care.
Professional advice may be particularly useful for:
- Solid-wall insulation
- Major retrofit projects
- Heat pumps
- Structural changes
- Older or traditional buildings
- Significant ventilation changes
- Solar installations
- Major electrical work
The right specialist depends on the work.
For major projects, independent advice can be particularly useful because someone selling a product naturally has an interest in selling that product.
Be Careful With Older Buildings
Traditional buildings can behave differently from modern homes.
Materials and construction methods may be designed to manage moisture in a particular way.
Therefore, applying a modern solution without understanding the existing building can create problems.
This does not mean older homes cannot be improved.
They often can.
However, the improvement needs to suit the construction.
So, for traditional or unusual properties, appropriate building knowledge becomes especially important.
Ventilation Must Remain Part of the Plan
As homes become better sealed, uncontrolled air leakage can fall.
That can be good for energy efficiency.
However, moisture still needs a way to leave the home.
Cooking, showering, drying clothes and even breathing add moisture to indoor air.
Therefore, an energy-efficiency plan should also consider ventilation.
This is particularly important when carrying out several improvements together.
A warmer home should also remain a healthy home.
Compare Quotes Properly
For larger projects, comparing several quotes can help.
However, do not compare only the final price.
Check whether each quote includes the same work.
For example:
- Materials
- Preparation
- Labour
- Scaffolding
- Electrical work
- Making good
- Waste removal
- Controls
- Commissioning
- Guarantees
One quote may look cheaper simply because important work has been left out.
Therefore, compare scope as well as price.
Ask What Is Not Included
This is one of the most useful questions you can ask.
A quotation may include the main installation but exclude related work.
For example:
- Decoration
- Electrical upgrades
- Scaffolding
- Repairs
- New controls
- Ventilation changes
These additional costs can significantly change the final price.
So, before agreeing to work, understand what you are actually buying.
Check Installers and Requirements
Some work must meet specific building, electrical, gas or other requirements.
Grants, warranties and finance schemes may also require approved installers or particular standards.
Therefore, check the requirements before work starts.
Do not assume that any installer offering the product automatically meets every requirement that may apply.
For regulated work, use appropriately qualified people.
Grants Can Change the Calculation
Financial support can make an improvement more attractive.
Depending on where you live and your circumstances, support may sometimes be available for measures such as:
- Insulation
- Heating
- Renewable technology
- Wider home-energy improvements
Schemes change over time.
Therefore, check current eligibility before starting work.
This is especially important because funding may not always be available retrospectively after you have already paid for an installation.
Don’t Let a Grant Decide What Your Home Needs
A grant can reduce the cost of an improvement.
However, something being subsidised does not automatically make it the right improvement for your property.
First ask whether the measure is:
- Suitable
- Needed
- Properly designed
- Compatible with the building
Then consider the funding.
Free or subsidised does not automatically mean appropriate.
Create a Long-Term Plan
You do not need to improve everything at once.
For many households, a staged plan is more realistic.
For example:
Now
Repair draughts and optimise heating controls.
Next planned work
Improve insulation when access becomes available.
Later
Replace heating equipment when the existing system reaches the end of its useful life.
Future
Consider solar, a heat pump or other technology alongside changing electricity needs.
Your actual plan may look completely different.
The important thing is that each decision supports the next one.
Keep Records
When work is completed, keep useful information such as:
- Invoices
- Product details
- Guarantees
- Installation certificates
- Photographs
- Commissioning information
- Instructions
For hidden work, photographs can be particularly useful.
For example, if insulation is later covered by flooring or plasterboard, evidence of what was installed may help in future.
Good records can also be useful when selling the property.
Measure What Happens Afterwards
Once an improvement is complete, see what changed.
Compare:
- Energy consumption
- Indoor comfort
- Heating times
- Room temperatures
- Draughts
- Moisture or condensation
Try to compare similar periods where possible.
For example, comparing one mild winter with one very cold winter may not tell you much without considering the weather.
Still, monitoring can help you understand whether the improvement is performing as expected.
Use Your Meter and Smart Data
Meter readings can help you monitor energy consumption.
If you have a smart meter, you may also have access to more detailed information through:
- An in-home display
- Supplier app
- Online account
This can help you see changes in energy use.
However, remember that household behaviour may change too.
For example, after insulation is installed, you may choose to keep the home warmer.
Your energy saving might then appear smaller, even though comfort has improved.
Therefore, measure both energy and comfort where possible.
Rebound and Comfort
Sometimes an efficiency improvement reduces the amount of energy needed to heat a home.
However, the household may use part of that benefit to become warmer.
For example, a previously cold bedroom may now be heated comfortably.
In that case, energy consumption may not fall by as much as expected.
That does not necessarily mean the improvement failed.
Part of the benefit has been taken as improved comfort.
This is another reason why energy efficiency should not be judged only by the next bill.
Priorities Can Change
Your plan does not need to remain fixed forever.
Circumstances change.
You might:
- Work from home
- Have children
- Retire
- Buy an electric vehicle
- Develop different accessibility needs
- Extend the property
- Change your heating system
Energy prices and technology can change too.
Therefore, review your plan occasionally.
A measure that made little sense five years ago may become worthwhile later.
A Simple Planning Process
If you are unsure where to start, use this sequence.
1. Understand
Learn how your home currently uses energy.
2. Investigate
Look for heat loss, draughts, faults and inefficient operation.
3. Repair
Deal with problems that should be fixed before improvements.
4. Prioritise
Focus on the improvements likely to provide the greatest overall benefit.
5. Cost
Get realistic prices and estimate likely savings.
6. Check suitability
Make sure the improvement works with the building and other systems.
7. Plan
Consider how today’s work affects future improvements.
8. Improve
Use suitable products and installers.
9. Measure
Look at energy use and comfort afterwards.
10. Review
Decide what, if anything, should come next.
Before Spending Thousands
Before making a major energy-efficiency investment, ask yourself:
- What problem am I solving?
- Do I understand what causes it?
- Can anything be repaired first?
- Is this improvement suitable for my home?
- What will it cost in total?
- What might it save?
- What other benefits will it provide?
- How long should it last?
- Does it need maintenance?
- Will it affect ventilation?
- Will it affect future heating plans?
- Is other building work planned?
- Have I compared suitable options?
If you cannot answer some of these questions, investigate further before signing a contract.
A little more time at the planning stage can prevent an expensive mistake.
In Short
There is no single energy-efficiency plan that suits every home.
Some properties need insulation.
Others need better heating controls.
Some have simple draughts or maintenance problems.
Others may benefit from major changes to heating or renewable technology.
Therefore, do not begin with a list of products.
Begin with your home.
Understand → Investigate → Prioritise → Cost → Improve → Measure
Use your bills, meter readings and EPC to build a picture. Then look at the condition of the property, its heating, insulation, ventilation, windows and doors.
Start with problems that need fixing.
Consider low-cost improvements, but do not assume the cheapest measure must always come first.
For larger investments, look at cost, energy saving, comfort, lifespan and future plans.
Most importantly:
Improve the home as a system, not as a collection of products.
Good energy efficiency is not about buying everything.
It is about making the right improvements, in the right home, at the right time.
Energility
Understand More. Spend Less. Live Better.