Self Assessment Energy Audit

Residential – Self Assessment Energy Audit

Written by M Stevens, BSc Building Surveying, 10 years Domestic & Commercial Energy Assessor, Director of Low Energy Supermarket Ltd

Please use our self assessment energy audit to see where you can save money and make your home

Energy efficient colour coding indicator – Red = Poor; Orange = Average; Green = Good; Blue = Not Applicable

Energy Consideration


Advice and Explanation


Typical average
savings per year


Almost Zero Energy or Carbon Negative House

Rural is the most exposed to high wind and colder temperatures, especially in coastal areas. It's even more important to be well insulated and draught sealed in these areas.
Low rise suburban areas will have some shelter to high winds from nearby properties
Normally most sheltered from high winds unless you are in a high rise building. Urban will usually be slightly warmer than outlying rural areas due to the heat island effect.
Type of Home
Detached houses and Bungalows have heat loss walls to all sides
Semi detached or end terraced houses typically have front, side and rear walls exposed to heat loss. Extensions will increase heat loss areas.
Mid terraced house or middle flats have the lowest area of walls exposed to the outside, which helps to reduce your heating bills.
Building Age
The older the property the likelihood of less or no insulation, unless it has been upgraded since construction. Some older extensions even with cavity walls were not insulated.
1983 to 2002 saw building regulations gradually requiring thicker and thicker insulation required during construction, but it was not always fitted pre 1990 so you should check inside wall cavities and roof spaces.
Newest construction, generally since 2003 have higher insulation standards, but still far from the highest passive house energy efficiency standards which we now need to meet zero carbon goals.
Window Glazing heat loss
Large areas of glazing should be kept to rooms which can be closed off from the rest of the building in very cold weather. Bigger windows, especially single glazed or old double glazing will have very high heat loss.
Most houses fit into this category. Consider heavy curtains over larger patio doors or windows to keep heat in at night.
No large areas of glazing or excessive rooflights. Highly insulated glass is expensive so it can be better to have smaller windows.
Sheltered, larger south facing windows, smaller glazing areas elsewhere, optimal volume for number of residents
Building Construction
Heating a conservatory is very inefficient as large glass areas lose heat very quickly. The heater will have to run almost constantly using lots of boiler gas power or electricity with high heating bills and carbon emissions. Having a conservatory open to the house will act a heat sink to the ground floor in cold weather causing draughts and very high heating bills.
Its best to let a conservatory heat up naturally with the warmth of sunlight. Ensure there is a double glazed door to seperate the conservatory from the rest of the house to keep excessive heat out in the summer and avoid excessive heat loss during the winter.
Separated from house and unheated. Maybe used to aid solar heating.
Loft Insulation to the Roof
Most heat is lost through your roof, so this is an important area to insulate. If you have no insulation, over £300 a year of heat could be lost through your roof and rooms below the roof will cool very quickly after heating is turned off. You may have good insulation to your main roof, but what about smaller inaccessible roofs or flat roofs. Insulation grants are available for this.
If you have an older standard of insulation like 100-150mm, this considered to be low nowadays. You should upgrade to minimum 270mm thick. An insulation grant maybe available for this. Flat roof areas before 1980's are unlikely to be insulated or minimal insulation which can be upgraded at the time of re-roofing. Larger areas of storage boarding will limit your insulation below, consider raising it with Loft Legs, see link
270mm thick within pitched roofs is typically at least 100 mm between ceiling joists and 150mm above. Also ensure your loft hatch is insulated above and draught proofed. Ensure you have 270mm insulation also below storage boarding, see Loftlegs link. Loftleg XL is also available for up to 400mm insulation below storage boarding.
450mm mineral wool
Measure your wall thickness at the window or doors. A 230-250 mm thick wall including internal wall plaster usually means the worst solid brick walls. This is the most expensive to insulate and requires thick external insulation with rendering or both internal and external insulation. Cavity wall bricks are laid so you can only see the long side of the bricks, solid walls show ends of bricks. A 275mm thick wall is usually a cavity wall with a thin 50mm cavity which can easily have injected insulated installed. Any cavity wall constructed before 1996 can be assumed to be uninsulated unless proved otherwise. Don't worry about dampness associated with injected cavity wall insulation as there are now very good bead insulation systems available which don't not encourage damp bridging. Grants are available. Older timber frame and system build walls will have limited insulation, although this is difficult to upgrade and perhaps can only be done with a new outer layer of insulation plus rendering.
A 275mm cavity wall needs both injected cavity fill insulation plus internal or external insulation sheets to be properly insulated. For older cavity walls, look for holes drilled at regular intervals in the mortar joints which indicate that injected insulation has already been installed in the past. The adequacy of insulation fitted to solid walls in the past can only be determined by core drilling a sample of the wall structure. Where solid walls have been insulated in the past, these may have only had minimal 25mm insulation backed plasterboard or similar whereas today's standard should apply 100mm PIR foam to inner or outer wall surface, or 50mm PIR foam to each side. Timber frame and system built walls can be upgraded using similar methods to solid walls, but vapour barriers/ breather membranes need to be applied to ensure no condensation within the wall.
300mm+ are usually cavity walls from around 1996 onwards which have a 100mm cavity and can achieve good insulation, but is still not the best. Current cavity wall construction is now starting to adopt 150mm highly insulated wall cavities using 100mm thick PIR foam insulation. A fully upgraded cavity wall to today's standard, in a pre 1996 construction will need a fully filled 50-75mm thick wall cavity plus internal or external insulation.
150mm mineral wool batts, 115mm aerated concrete blocks and inner 40mm PIR foam backing to plasterboards OR 3 layers of 100mm mineral wool quilt within timber frame construction, fully air sealed with membranes.
15% of heat is lost through the floor. Most solid concrete floors before 1990 are unlikely to be insulated. Solid floors can only be insulated from above with 25mm PIR foam and new boarding below finished flooring but this involve adjusting doors. It is often quite easy to insulate below suspended timber floor if there is sufficient access into the floor void or cellar below.
You should have at least 100mm mineral wool quilt insulation supported below suspended timber floors. 1990 onwards should have 50-150mm thick insulation below solid concrete floors.
150-200mm thick polystyrene type insulation should have been fitted below solid floors in new houses and extensions from around 2002 onwards.
200mm expanded polystyrene below concrete slab
Single glazed windows have very high heat loss and are very draughty. Perhaps these are unavoidable in a listed building or conservation area but you can still apply glazing film or secondary glazing and heat reflective films.
Old double glazing before around 2002 had a 8mm air gap. Double glazing after 2002 should have a 16mm air gap with heat reflective low emissivity glass, which helps to reflect heat back into the building, saving 50% more heat than old double glazing. A low emissivity glass tester costs around £80, but you could ask an EPC energy assessor to come by and check your glazing for a small charge as they will carry one,
16mm air gap with low emissivity glass is good, as long as the window areas are not too big.Triple glazing is best.
Triple glazing (with a good solar heat-gain coefficient, low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and ‘warm edge’ insulating glass spacers.
Timber doors have the highest heat loss. Wooden panelling to doors is often very thin, losing heat quickly. Doors have a fairly large surface area, which is why insulated doors are recommended.
Most UPVC doors should be a composite construction with a thin layer of insulation between two layers of plastic sheet, but it is often very difficult to be sure unless you can work out the panel thickness.
Modern UPVC doors or composite doors should be well insulationed. Check for any certification or manufacturer's data to confirm.
Fully insulated
Mechanical ventilation uses electricity and causes heat loss by extracting warmed air if there is no heat recovery.
Natural ventilation means opening windows sometimes during colder weather therefore losing heat
MVHR can use very little electricity to run the fans and can recover over 75% of the heat from extracted air to pre-heat the incoming air using a heat exchanger. To have a very energy efficient house, it is necessary to completely weatherseal all windows, doors, and wall / ceiling and floor junctions.
Mechanical ventilation with Heat Recovery (MVHR)
Draught Proofing
If your house is draughty, you will notice it is much cooler inside during cold or windy weather. Rubber or foam draught seals should be in place around all window and door openings. Larger gaps to older windows can be filled. You may wish to draught seal some internal doors to keep certain habitable rooms warmer, like the living room. Draught strips are also available for older wooden floor boards and floor perimeters.
Check all windows, doors, loft hatches have draught strips. Perhaps only some have been fitted in the past. Also fill any cracks around or below windows and doors. Also seal floor perimeters, below skirting boards.
Once you are fully draught sealed, this is good for being energy efficient and reducing your, but it can also lead to poor internal air quality. This is where the most insulated homes need something like the MVHR ventilation system mentioned above.
Extremely airtight. sealed to 0.60 air charged per hour at 50 pascals
Heating Systems
Fuel Type
Direct electricity heating is the most expensive to run, unless you are super insulated. Oil or LPG heating in rural areas is the worst for the environment with fossil fuel emissions to deliver the fuel, then more fossil fuel emissions to burn it. Instead, investment in a wood chip or wood pellet boiler is cost effective by switching to a renewable fuel source which can be managed and re-grown. Alternatively consider an electric heat pump, see below. Avoid coal burning, unless space restrictions means there is no alternative.
The vast majority of houses have natural gas heating, but this is a long term issue the government has to deal with in order to phase out fossil fuels over the next 15-20 years. Mains gas is the most realistic option for many, which can be efficient with good insulation and effective thermostat/ programmer controls. Eventually, gas will be replaced with blue or green hydrogen.
Biomass is wood chip or wood pellet boiler and considered a renewable fuel source which can be re-grown. Electricity used with a heat pumps can be the most efficient when combined with very good insulation.
Electric heat pump and perhaps a wood burner
Gas Heating Boiler Efficiency
Any pre 1998 boiler is considered to be very inefficient. Don't take advice from heating engineers who tell you 'that's a good quality boiler which is not worth replacing'. An old boiler can use 25% more gas, and with current gas prices, that could mean £250-£300 a year more to run. Some range cookers can use up to 40% more gas then a modern condensing boiler, which could be £400 a year more to run with high carbon emissions.
Grants are available to replace older boilers with a condensing boiler
Some condensing regular or combi boilers now over 90% efficiency. If you can get a hydrogen boiler, ensure it is fuelled with Blue or Green hydrogen as Grey hydrogen is manufactured by burning gas or methane with its associated carbon emissions and therefore has no environmental benefit.
£115-250 per year?
Heating thermostat and programmer controls
Don't set your heating temperature too high. It should not be more than 21 deg C or keep just one room warmer. Most families are happy with a setting somewhere between 18˚C and 21˚C for most of the home. Turning you heating down by 1 degree C could save £80 a year. The higher your internal temperature, the more fuel you will use.
As a minimum, you should have a heating programmer and central thermostat control.
The most efficient way is to control the heating time and temperature room by room.
Full thermostatic programmer controls. How house should stay warm due to high standard of insulation.
Secondary Heating
Open fires means an open chimney flue. You may even be able to see daylight if you look up the chimney. This is a big hole in your house allowing lots heat to escape. Use a Chimney Sheep or Chimney Balloon to block the flue when not in use. Some older decorative gas fires also have open chimney flue which should be blocked when not in use.
An open flue wood fire uses a renewable fuel to make heat, but it is only around 20% efficient. This means 80% of the heat goes straight up the chimney. Gas fires sealed to the fireplace opening reduce the amount of air and heat allowed to escape up the chimney, but are still considered fairly draughty.
You can help to offset your fossil fuel emissions by having a log burner sealed to chimney or pellet stove. This means you can reduce usage of your main heating fuel if it is gas, oil, LPG or electricity.
Wood burner optional
Hot Water heating fuel
Electric hot water immersion heaters are normally used when there is no gas or heating boiler. An immersion heater needs to have a well insulated storage tank and a timer switch or programmer to control when the electric heating is turned on.
Most houses commonly have gas fired combination boilers. Some new houses have separate hot water cylinders heated from the main boiler which gives faster hot water delivery but has higher associated heat losses throughout the year.
The most efficient hot water comes from solar water heaters. These do require space for a hot water storage cylinder. Solar heat is collected from flat plate connectors or evacuated tubes which use black backgrounds to absorb heat from the sun.
Solar hot water heating with electric immersion booster/ timer switch
Hot Water Storage Cylinder Insulation
No hot water insulation with electric heating is effectively direct electric heating to your house and cost as much as £56 a week to run! Either dont turn on the hot water or fully insulate as soon as possible.
Most hot water jackets are to BS 5615 and are 80mm thick. This is a 1985 standard. Today, we'd recommend doubling this to 160mm thick by fitting an additional jacket over the top of existing jacket or foam insulation.
Aim or 30-50mm foam and 80mm mineral wool jacket or 2x80mm insulation jackets.
150mm jacket
Hot water cylinder thermostat
If you have electric immersion heating, the thermostat is built into the heating element. If hot water is heated from your boiler, a thermostat should be attached mid-height around your hot water cylinder and this turns off the heating water flow to the cylinder once it reaches sufficient temperature, therefore allowing your boiler to use less gas. This thermostat maybe hidden beneath the jacket.
Cylinder thermostat is fitted.
Built into immersion heater
Shower head water flow rates
Electric showers are typically 8.5 to 10.5kw. This is as much as 10500 watts of electricity which costs around 3p per minute, or 24p for your average shower, or £88 per person per year for one shower a day. A standard hot/cold mixer shower head may have a flow rate as high a 12 litres per minute or more, especially in areas of high water pressure. This also allows full hot water flow from your boiler giving maximum gas usage for the duration of your shower.
Get a flow rate testing bag or fill a bucket for 1 minute and measure how many litres of water was used to find your litres per minute.
For a gas powered hot water boiler, a shower with an average flow rate will cost around £49 per person per year. I bath will use around two to three times as much hot water than a shower, therefore costing at least twice much.
6 litres per minute water flow rate shower head and 4 to 5 minute showers is the best most people can do. Less water usage means both metered water and hot water savings.
6L/minute flow rate
Types of lighting and how many lights
If you still have any old halogen or tungsten lights, throw them away now. LED and CFL lighting can use 10 times less electricity. Also change any old halogen flood lights to LED lighting. LED tube lights can use 35% less electricity than fluorescent tubes.
Aim for the highest efficiency lighting throughout your home. Get rid of any old halogen or tungsten filament lighting now, especially if it is often used.
LED bulb, panel, strip lights and floodlights are the best for the environment using the lowest amount of power.
LED Lighting
Renewable Green Energy Sources
Solar Photovoltaic Panels
Solar panels are long considered the be cheapest option to get green electricity into your home. Also consider getting solar panels with a battery storage system so you can also use your solar power overnight. In the summer months, with solar power and battery storage, you will often find you do not use any grid supplied electricity at all, which is a great feeling. You can be 100% carbon neutral or even carbon negative.
If you already have solar panels fitted, do you have enough kilowatts of generation? Could you fit more, or perhaps have a ground mounted solar array in addition to panels on your house, if you have the space. Maybe you have solar panels fitted, but you are exporting half of your electricity. Consider getting around 6 to 10 kilowatt hours of battery storage to help you to use your solar power generation overnight.
Ground or roof mounted system with battery storage
Occupancy Savings
Clothes drying
Tumble dryers use lots of electricity, they are bad for the environment, and they damage clothing fabric turning it into blue fluff which get caught in the filter.
Some people chose to tumble dry only small items like socks and underwear, or use a tumble dryer for quick clothes drying where needed.
Completely free to dry your clothes outside or hang them inside during winter, just like the generations which have done for hundreds of years before us.
Natural air drying outside or internal clothes airers. Never use a tumble dryer.
This wastes electricity, especially if any of your lighting still uses older tungsten or halogen lighting.
Maybe you have efficient CFL or LED lighting, but some lights still get left on.
Consider fitting motion detectors to your lighting, or use smart lighting which can be programmed with on/ off times.
Full LED lighting with occupancy sensors.
Heated Habitable rooms
How much of the house is heated? Often people may heat the whole house every time the heating comes on, but do you need to heat all of it? Heating only half of the house, or only heating rooms when you are actually occupying them can use half as much energy, saving around £300 a year for the average house.
Maybe some rooms have no heater or radiator. These could occasionally be heated with an electric heater if they are rarely used, which is ok. Maybe you are making good use of your thermostatic radiator valves and turning them right down in rooms which are rarely used.
The most advanced heating control, can decide on the time and temperature when you want the heating to come on in each room.
All if needed with good controlsny

Property Score

* For accurate advice on Passivhaus design, engage the services of a certified Passivhaus consultant.

Net Zero

You are 0% of the way towards being a Net Zero home!
(Above scores are for guidance only to help you on your energy reductions journey)
Additional Suggestions
Fit radiator reflector panels to reflect heat back into the room£25-35
Insulate your hot water pipes anywhere you can access the, especially if they pass through a cold roof space or garage. This ensure the heat gets to the place where you need it, rather than losing heat along the way which uses more heating fuel.£15-25
Monitor your energy using a smart meter. Identify which appliances use the most electricity.
Always run your washing machine and dishwasher with full loads.
"Adjust your fridge temperature to between 3°C and 5°C. If colder, more energy is used while higher temperatures allow food poisoning bacteria to grow. Use a fridge thermometer to check the temperature."£5-10
"Adjust your freezer temperature to between -15°C and -18°C. Use a fridge thermometer to check the temperature"£5-10
"Turn appliances off at the wall to prevent standby power use. Use an energy monitor to measure standby power use"
Run wood burners at optimal temperature by using a flue pipe thermometer

Help with upgrading your home, making it Greener and more energy efficient.

Some work may need to be self funded, but if your money is spent well, you will save money though your heating and electricity bills. There are also many home energy grants available if you are a private or council tenant or if anyone living at the property receives benefits. See for more information.