Pilkington Suncool solar control glass in Wolverhampton

Think of it as a routine rather than one trick. Close windows, blinds and curtains on the sunny side of the house from mid-morning, because once outdoor air is hotter than indoor air, ventilation works against you. Open everything up in the evening and overnight to flush the day’s heat out, ideally with windows open on opposite sides of the house for a through-draught. Switch off ovens, tumble dryers and anything else generating heat, and swap thick bedding for a sheet.

All of that manages heat after it arrives, though. Most of it comes through your glass, because ordinary glazing lets the sun’s energy straight in, where it gets trapped. The one permanent, natural fix is glass that reflects heat away, which is exactly what Pilkington Suncool does. No power, no maintenance, just a coating doing the work all day while you get on with your life.

Night cooling is really about what you did during the day. A bedroom that’s stifling at 11pm banked that heat hours earlier, when sun came through the glass and warmed the walls, furniture and mattress. All evening, they release it back at you.

So fight the battle in daylight: blinds and windows closed on the sunny side from mid-morning, then open windows on opposite sides of the house as soon as the outside air cools, usually early evening. A fan near an open window pulls cooler air through faster. Upstairs rooms need the longest flush because heat from the whole house rises into them.

If the room still won’t cool, stop the heat getting banked in the first place. Solar control glass like Pilkington Suncool reflects most of the sun’s heat at the window during the day, so by bedtime there’s simply less stored heat for the room to release.

Closed by day, open by night. It feels backwards, but the rule is simple: only open windows when the air outside is cooler than the air inside. During the hottest part of the day an open window is a radiator, pouring warm air into the house. Keep windows shut through the afternoon, with blinds or curtains drawn on the sunny side, then open up in the evening once the temperature drops. Windows open on opposite sides of the house create a cross-breeze that clears heat far quicker than one window alone.

One thing opening and closing can’t control is radiation. Sunlight passes straight through ordinary glass whether the window is open or not, which is why a closed room with big glazing still cooks. Pilkington Suncool reflects most of that heat at the pane itself, which makes the whole open-shut routine matter a lot less.

It comes from NHS heat advice: the sun is at its strongest between 11am and 3pm, so that’s the window when you should stay out of direct sun, keep to the shade, and keep your house defended. In practice it means blinds down and windows shut on sun-facing rooms before 11am, strenuous jobs done early or late, and children, older relatives and pets kept out of the midday heat.

It’s good advice, and worth following. But notice what it really is: a daily rota for managing heat your house can’t handle on its own. The homes that cope best in a heatwave don’t rely on remembering rules by the clock. Glazing that reflects the sun’s heat, like Pilkington Suncool, defends those rooms automatically from 11am to 3pm and every other hour, whether you’re home or not.

Deal with the causes in order of size. The biggest is solar gain through glass: sun streams through windows, doors and conservatory roofs, turns to heat indoors and can’t get back out. Then internal heat sources, ovens, dryers, and electronics. Then ventilation habits, opening windows at the wrong time of day.

So: shade or shut sun-facing glazing by day, ventilate hard in the evening, cook outside or eat cold when it’s really hot, and run heat-producing appliances at night. External shading such as awnings beats internal blinds, because it stops heat before the glass rather than after.

For a permanent version of that external defence, change what the glass itself does. Pilkington Suncool reflects most of the sun’s heat away while letting daylight through, and across the range you can choose how much protection each room needs. It’s the difference between managing a hot house and not owning one.

A little, briefly, and only right next to the fan. Air blown over ice does pick up some chill, so you’ll feel a cooler breeze for as long as the ice lasts, which on a hot day isn’t long. It won’t lower the temperature of the room, and once the ice melts you’re back to a fan pushing warm air around, plus a bowl of water raising the humidity, which actually makes sweating less effective.

It’s fine as a quick fix for one person at a desk. It’s not a cooling strategy. The room is hot because solar heat came through the glass all day and got trapped, and no bowl of ice is a match for that. Stopping the heat at the window is what changes the room. That’s the job solar control glass does, permanently, without a freezer run every two hours.

UK homes are built for cold, which is exactly why they struggle: insulation designed to trap winter warmth traps summer heat just as well. In extreme heat, run the full defence. Windows and blinds shut on the sunny side by mid-morning, ventilate only in the evening and overnight, heat-producing appliances off, and check on older relatives and neighbours, because the UKHSA is clear that older people are most at risk when homes overheat.

The West Midlands has had some of the worst heat-related death figures in England in recent years, so this isn’t a southern problem. And with hardly any UK homes having air conditioning, the fabric of the house has to do the work. Glazing is the weakest point in that fabric, and it’s fixable: Pilkington Suncool reflects most of the sun’s heat at the window, upgrading the house itself rather than your coping routine.

For a single stubborn room, stack the basics. Blinds or curtains closed whenever the sun faces that window. The window itself shut during the day and open in the evening. A fan positioned to pull cooler air in from a shadier part of the house rather than just stirring the warm air. Doors open to let heat escape to cooler rooms, and anything that generates heat, from games consoles to chargers, switched off properly.

If it’s a south or west-facing room, though, you’re managing a glass problem with fabric solutions. The sun delivers its heat through the window pane, and blinds only intercept it after it’s already indoors. Solar control glass stops it at the point of entry. Pilkington Suncool reflects most of the sun’s heat while keeping the room bright, which for one overheating room is a smaller job than most people assume: it’s a glazing swap, not a building project.

The Lullaby Trust recommends a baby’s room sits between 16 and 20°C for safe sleep, which UK summer bedrooms regularly blow past. Keep the nursery’s blinds and window closed through the day if it faces the sun, then ventilate in the evening before bedtime. A fan is fine for moving air, aimed to circulate rather than blow directly at the cot. Dress the baby in fewer layers, use a low-tog sleeping bag or just a sheet, and check their chest or neck for overheating rather than hands, which run cool.

A room thermometer takes the guesswork out. If the nursery still reads hot at bedtime despite all of it, the room is storing solar heat from earlier in the day, and that’s a glazing issue. Suncool glass reflects the sun’s heat before it enters, which keeps a nursery’s baseline temperature down without you managing it hour by hour.

Dogs can’t sweat like we do, so an overheating house is harder on them than on you. Keep them out of conservatories and sun-facing rooms entirely during hot spells, because those rooms can reach dangerous temperatures shockingly fast. Fresh water always down, walks shifted to early morning and late evening when pavements won’t burn paws, and cooling mats or damp towels for them to lie on. Flat-faced breeds like pugs and bulldogs need extra caution, as they struggle most in heat.

Remember dogs are home all day, often shut in one or two rooms while you’re out, with no way to open a window or move somewhere cooler. That’s a strong argument for making the rooms themselves safe rather than relying on being there. Solar control glazing keeps those rooms from climbing while you’re at work, which is precisely when your dog needs it.

Work through it in order. First, stop losing the heat you’re paying for: draught-proof doors, letterboxes and unused chimneys, close curtains at dusk, and make sure radiators aren’t blocked by sofas or coated in drying washing. Second, check the heating is working properly, radiators bled, boiler serviced, thermostat somewhere sensible rather than in the coldest hallway. Third, heat the rooms you live in properly rather than the whole house weakly.

If you’ve done all that and rooms still won’t hold warmth, the fabric of the house is leaking it, and glazing is one of the biggest culprits. Older double glazing loses far more heat than modern coated glass. Today’s low-emissivity units, including Pilkington Suncool at a Ug value of 1.0 W/m²K, reflect your radiators’ warmth back into the room instead of letting it drain through the window. Same radiators, warmer room.

The cheapest heat is the heat you don’t lose. Draught-proofing strips, a letterbox brush and a chimney balloon cost a few pounds and pay back fast. Thick curtains closed at dusk, rugs on bare floors, radiator reflector panels behind radiators on external walls. Heat the rooms you use and close doors to the ones you don’t. Layers and a heated throw cost pennies against putting the whole thermostat up a degree.

Then rank the bigger jobs by payback. Loft insulation is usually first, it’s cheap and lofts leak badly. Then draughty floors, then walls, then glazing. Windows come later on cost, but they’re the fix you feel most, because cold glass makes a room feel chilly even when the air is warm. Modern coated units like Suncool reflect room heat back inwards, so when your windows are due anyway, that’s the moment to buy the warmth.

For most homes, no. The Energy Saving Trust’s advice is that heating only when you need it is cheaper than running it low around the clock, because a house leaks heat constantly, and the longer the heating runs, the longer you’re paying to replace what’s escaping. Use timers so the house warms up shortly before you get up and get home, and let it rest in between.

The exception is a very well-insulated house, where so little escapes that a steady low burn can make sense. Which points at the real answer: the argument is entirely about how leaky your house is. Fix the leaks and both approaches get cheaper. Windows are a significant part of that, since glass sheds heat faster than an insulated wall. Modern low-emissivity glazing like Suncool cuts what escapes, which shrinks the bill whichever heating pattern you run.

You don’t need heating running all night for comfort in most homes, a bedroom around 18°C at bedtime and decent bedding will carry you through. What freezing weather does justify is protecting the house: in a hard frost, many people set the heating to come on low overnight or use the boiler’s frost setting, so pipes in lofts and cold spots don’t freeze and burst. That’s insurance, not comfort.

If your bedrooms genuinely can’t hold warmth from a 10pm heating cut-off to morning, the house is losing heat too fast, and that’s worth fixing rather than funding. Check loft insulation above the bedrooms first, then the windows. A cold pane pulls heat out of a room all night and creates that chilly draught you feel near the glass. Low-emissivity units such as Suncool reflect warmth back into the room, so what you heated in the evening is still there at 3am.

In a typical uninsulated house, the walls lose the biggest share overall, with the roof close behind, then windows, draughts and floors making up the rest. That’s why loft and wall insulation top most energy advice lists: they cover the largest areas.

Windows deserve a special mention though, because per square metre, glass loses heat faster than any other part of the building. A single pane leaks warmth many times quicker than an insulated wall, and even older double glazing is poor by modern standards. It’s also the loss you feel: sit near a cold window and the chill is immediate, which pushes people to turn the thermostat up for the whole house.

So insulate the loft first if it isn’t done. But when windows are on the list, specify glass that works: modern coated units like Pilkington Suncool hold heat in with a Ug value of 1.0 W/m²K.

A house that warms up but won’t stay warm is telling you where the heat is going, so play detective. Rooms that cool within an hour of the heating clicking off point to fabric losses: check the loft insulation depth, feel for draughts at skirting boards, floors and around window frames, and put your hand near the glass, because a cold pane means heat is pouring out there. Radiators cold at the top need bleeding. A house that’s cold in patches usually has an unbalanced heating system rather than a broken one.

Older windows are a common answer. Glass from twenty-plus years ago loses heat far faster than today’s coated units, and failed sealed units, the ones with misting between panes, are worse again. Modern low-emissivity glazing such as Suncool reflects your heating back into the room, which turns “warm while it’s running” into “warm all evening”.

Yes, genuinely. Public health guidance recommends keeping the rooms you live in at 18°C or above in winter, because prolonged cold at home is linked to raised blood pressure, heart and lung problems, worsened arthritis, and damp and mould that trigger respiratory conditions. The risks are highest for older people, young children and anyone with an existing health condition, and the UK records thousands of excess winter deaths in cold years. A cold home is a health issue, not a comfort preference.

Damp is the visible warning sign: condensation streaming down cold glass every morning means the room is both cold and wet, a combination mould loves. Warming the fabric of the house breaks that cycle. Insulation and decent glazing keep surfaces warmer so moisture stops condensing on them. Modern coated units hold room heat in, which protects the people in the house as much as the house itself.

Health guidance draws the line at 18°C for living areas: below that, risks to health start climbing, especially for older people, babies and anyone with heart or breathing conditions. So 17°C is below the recommended minimum, 14°C is firmly into the zone where health effects are documented, and 13°C or lower is a house that needs action, not extra jumpers. Bedrooms can run slightly cooler overnight for healthy adults, but living rooms shouldn’t.

If you’re reading those numbers on your own thermostat, the question is why the house can’t hold 18°C affordably. Sometimes it’s the heating system, but more often the house is shedding heat as fast as you make it, through the loft, walls, draughts and glazing. Each one you fix makes 18°C cheaper to hold. Windows are the fix you feel fastest, because warm glass removes the cold zones that make rooms feel worse than the thermostat claims.

Split it into free wins and proper fixes. Free wins: curtains closed at dusk and open to south-facing sun by day, draughts blocked, radiators bled and unblocked, doors closed to unused rooms, reflector panels behind radiators on outside walls. These can lift a room a degree or two by themselves.

Proper fixes, in rough payback order: loft insulation topped up to current standards, draught-proofing done thoroughly, wall insulation where the house suits it, and then the glazing. Windows are where cold gets personal, the draught you feel on the sofa, the chill radiating off the pane, the condensation every morning, so upgrading them changes how warm the house feels, not just what the thermostat says.

Modern glass does the heavy lifting: Pilkington Suncool holds heat in at a Ug value of 1.0 W/m²K, and the same coating keeps the house cooler the following July. One upgrade, both seasons.

Time the heating rather than running it late: warm the bedrooms in the hour before bed, then let the system rest, because a decent duvet does the overnight work far cheaper than a boiler. Close every curtain in the house at dusk, since bare glass sheds heat all night. Shut bedroom doors to keep the warmth you’ve built, and put a thicker tog on the bed instead of a degree on the thermostat. An electric blanket costs pennies a night against heating a whole room.

If bedrooms are freezing by morning despite all that, the room is leaking. Bedroom windows are prime suspects: you spend eight hours next to a large cold surface that pulls heat from the room and drops chilled air onto the bed, which is that draught you feel with the window firmly shut. Low-emissivity glazing reflects the room’s warmth back in, so the heat you paid for at 9pm is still around at 6am.