KiloWiseHeating vs cooling: a seasonal checklist (winter + summer)
KiloWise editorial team · Last updated 5 November 2026 · Category: Heating & Cooling
Energy saving has a season to it. The things that matter in January — draughts, frozen pipes, a boiler that has not been serviced — are not the things that matter in July, when the question is how to stay cool without running the air conditioner all day. Most homes waste money in both seasons, but for opposite reasons: in winter they heat air that leaks straight outside, and in summer they cool rooms nobody is sitting in.
This is one checklist for both seasons, designed to be printed and worked through twice a year — once in autumn, before the heating season, and once in spring, before the cooling season. Every item is a job you can tick off, in roughly the order that matters most. Nothing here needs a big spend to start: the first items in each section are free, and the ones that cost money say so plainly.
Use it alongside the two guides that go deeper on the two biggest items: thermostat settings to save money for the temperatures behind the checklist, and how to save money on water heating for the hot-water items in the winter section. This page is the plan; those pages are the detail.
Winter checklist: heating, draughts and pipes
Do this section in autumn, before the first cold snap. The aim is simple: keep the heat you pay for inside the house, and make sure nothing freezes or fails when the temperature drops.
Heating
☐ Book a boiler or furnace service before winter, not during it — engineers are booked solid once the cold arrives, and a service catches the faults that become midwinter breakdowns. ☐ Bleed your radiators: if the top is cold while the bottom is hot, trapped air is stopping them working, and bleeding takes five minutes with a radiator key. ☐ Set your thermostat to the DOE starting point of around 68°F (20°C) when home and awake, and programme a setback of 7–10°F for the hours you are asleep or out — the full settings are in our thermostat guide. ☐ Check that radiators are not blocked by furniture, curtains or drying clothes, which trap the heat against the wall instead of letting it into the room. ☐ If you have a heat pump, remember the exception: no deep setback without a smart thermostat designed for heat pumps, or the recovery will call on expensive auxiliary heat.
Draughts
☐ Walk the house on a windy day with a lit incense stick or a damp hand and find where cold air comes in — windows, doors, letterboxes, keyholes, loft hatches and gaps around pipes are the usual suspects. ☐ Fit draught excluder strips to doors and windows that leak; fit a brush or flap to the letterbox and a cover to unused keyholes. ☐ Close the curtains at dusk and open them on sunny mornings — curtains are free insulation at night and free solar heating by day. ☐ Block unused chimneys with a chimney balloon or a fitted draught excluder, and remember to remove it before lighting a fire. ☐ Check the loft hatch: an unsealed hatch leaks warm air into a cold loft all winter, and a strip of draught-proofing tape around it is a ten-minute fix. The cheapest draught fixes, in order, are in our guide to draught-proofing.
Pipes and water
☐ Insulate exposed pipes in unheated spaces — lofts, garages, outbuildings — with foam pipe lagging, so they do not freeze and burst. ☐ Know where your stopcock is, and check that it turns; if a pipe does burst, shutting the water off in the first minute is the difference between a puddle and a flood. ☐ Check your hot-water tank temperature is at 60°C/140°F if you have a stored tank — never lower it to save money, because of the legionella risk explained in our water-heating guide. ☐ Insulate the tank and the first run of hot-water pipes if the tank feels warm to the touch. ☐ Set the heating to at least 55–60°F if you go away in winter, rather than switching it off entirely; frozen pipes cost far more than the heating you save.
Pre-winter check
☐ Test the heating a month before you need it — switch it on for an hour in early autumn and listen for odd noises, cold radiators or a boiler that will not fire. ☐ Check window and door seals for cracks or gaps that opened over the summer. ☐ Clear leaves from gutters and drains so rainwater runs away from the house instead of pooling against the walls. ☐ Stock the basics: a radiator key, spare draught strips, pipe lagging, and the phone number of your heating engineer. ☐ Read your meter and note the reading, so you can compare this winter's use with last winter's and see whether the checklist worked.
Worked example: what the winter setback is worth on a stated heating and cooling cost
Take a household whose annual heating and cooling cost is $1,000 a year — a stated assumption for this example, not an average; enter your own figure from your bills. The DOE says a setback of 7–10°F for 8 hours a day can save up to 10% a year on heating and cooling, as an upper figure, not a promise.
FORMULA: $1,000 per year × 10% (DOE upper figure) = $100 per year
Result: at the DOE's upper figure, the winter setback alone could save up to about $100 a year for this household. Using the 1%-per-degree rule of thumb, a 7°F setback suggests roughly 7% of $1,000, which is $70 a year. Both are estimates, and the draught-proofing and pipe insulation in the checklist above save money on top of the setback by reducing the heat the system has to replace — but those savings have no verified figure attached, so they are not included in this arithmetic.
Summer checklist: cooling without running AC all day
Do this section in spring, before the first heatwave. The aim is the opposite of winter's: keep the heat out during the day, let the cool air in at night, and only cool the rooms you are actually using.
Keep the heat out
☐ Shade the sunny side: close blinds or curtains on south- and west-facing windows (north-facing in the southern hemisphere) before the sun hits them, not after the room is already hot. ☐ Use external shading where you can — an awning, a shade sail or even a light-coloured sheet outside the window beats any curtain inside, because it stops the heat before it reaches the glass. ☐ Keep windows closed during the hottest part of the day if the outside air is hotter than the inside air; open them when the outside cools. ☐ Turn off heat you do not need: ovens, tumble dryers and old incandescent bulbs all add heat to a room that the air conditioner then has to remove — cook outside or use a microwave on the hottest days, and dry clothes on a line. ☐ If you are replacing bulbs anyway, LEDs run far cooler than halogens as well as using less electricity.
Night ventilation
☐ Open windows on opposite sides of the house at night to create a cross-breeze, and close them in the morning before the day heats up — this is the single most effective free cooling trick in a climate with cool nights. ☐ Use window screens if insects are a problem, so you can leave windows open overnight safely. ☐ If nights stay hot and humid, night ventilation helps less, and a fan becomes the better tool — see the next section. ☐ In a flat with windows on one side only, a fan in the window blowing outwards at night pulls cooler air in through the door or hallway. ☐ Never leave ground-floor windows open overnight if that is a security risk in your area; a locked window vent or a fan is the safer alternative.
Cool only the rooms you use
☐ Set the thermostat to around 78°F (26°C) when you are home, per the DOE's summer starting point, and set it up by 7–10°F while you are out or asleep. ☐ Close the doors of rooms you are not using, and do not cool them — there is no reason to air-condition an empty bedroom all afternoon. ☐ Use a fan before reaching for the air conditioner: moving air makes 78°F feel several degrees cooler, and a fan uses far less electricity than an AC unit. ☐ If you have a portable AC, vent it properly out of a window — an unvented unit dumps its hot exhaust back into the room it is trying to cool. ☐ Dress for the season indoors: light clothing and bare feet change what 78°F feels like, just as a jumper changes what 68°F feels like in winter.
Filters and the AC itself
☐ Clean or replace the air conditioner filter at the start of the season and monthly through summer — a clogged filter makes the unit work harder, cool worse and use more electricity. ☐ Clear leaves and debris from around the outdoor unit so air can flow freely, and hose the fins gently if they are dirty. ☐ Check that the condensate drain is clear; a blocked drain can leak water indoors. ☐ If the AC is old and struggles even with a clean filter, get it serviced before the hottest weeks rather than during them — and check whether a newer unit would be worth it, since efficiency has improved a lot. ☐ At the end of summer, clean the filter once more and cover the outdoor unit if your climate has harsh winters.
| Season | Do first (free) | Do next (cheap) | Check before the season |
|---|---|---|---|
| Winter | Thermostat setback; close curtains at dusk; bleed radiators | Draught strips; pipe lagging; tank jacket | Boiler service; stopcock turns; heating test-run |
| Summer | Shade sunny windows; night ventilation; fans before AC | AC filter clean; window screens; LED swaps | Outdoor unit clear; condensate drain clear |
How to use this checklist year after year
Print this page, or copy the two sections into a note, and put a date on it each time you work through it — once in autumn, once in spring. Tick items off as you go, and add a line at the bottom for your meter reading at the start of each season, so you can compare this year with last year. The checklist is deliberately the same every year: the jobs do not change, and the value is in doing them before the season starts rather than in the middle of it.
If you find the same items undone every year — the filter never cleaned, the draught strips never fitted — do not add more items; do fewer, earlier. Pick the three free items in each season and do them in the first weekend of autumn and spring. Three jobs done beat twelve jobs planned.
For the detail behind the checklist, the thermostat guide covers the temperatures and the setback maths, the water-heating guide covers safe tank temperatures and insulation, and the whole-home audit at whole-home energy audit will show you which season costs your household more. Our resources page collects the checklists and tools in one place.
Frequently asked questions
When should I do the winter energy checklist?
In early autumn, at least a month before you expect the first cold weather. That leaves time to book a boiler service, order draught-proofing and test the heating while engineers still have appointments — and to fix anything that fails before you actually need the heat.
Does closing curtains really help in summer?
Yes, if you close them before the sun hits the window, not after the room is already hot. Curtains and blinds inside the glass help, but shading outside the window — an awning, a shade sail, even a sheet — helps more, because it stops the heat before it reaches the glass at all.
Is it cheaper to leave the AC on all day or turn it off when I go out?
Turn it up, not off, while you are out: set it 7–10°F higher than your home setting, per the DOE's setback advice, so the house does not get so hot that cooling it back down costs more than you saved. If you have a heat pump, keep the change small and gradual, as with winter setbacks.
How often should I clean my AC filter?
At the start of the cooling season and monthly through summer. A clogged filter restricts airflow, so the unit runs longer and cools worse. It is a five-minute job on most units — check your manual for where the filter sits.
What is the one winter job people skip that costs them most?
Finding the draughts. A house can lose a large share of its heat through gaps around doors, windows and the loft hatch, and the fixes — draught strips, a letterbox brush, tape around the hatch — are among the cheapest in this whole checklist. Walk the house on a windy day and find them before winter, not during it.
Sources
- US Department of Energy — thermostat guidance: winter around 68°F when home and awake, summer around 78°F, setback of 7–10°F for 8 hours a day can save up to 10% a year on heating and cooling; heat-pump setback caution. Cited from DOE guidance current at November 2026.
- ENERGY STAR — heating and cooling account for roughly half of a typical home energy bill. Cited from ENERGY STAR guidance current at November 2026.
- UK Health and Safety Executive — hot water should be stored at 60°C or higher; Legionella multiply between 20°C and 45°C. Guidance current at November 2026.
Related: the temperatures behind this checklist are in our guide to thermostat settings to save money, hot-water items are covered in how to save money on water heating, and the printable versions live on our resources page.