Right then, let's get this sorted. Grab a cuppa and a biscuit, and let's settle one of the greatest British winter debates of all time.
The Great British Heating Debate: Is It Cheaper to Leave It On Low All Day?
Ah, winter. The season of cosy jumpers, dark evenings, and that one argument that splits families, sparks pub debates, and has been passed down through generations like a questionable heirloom: the central heating strategy.
We’ve all been there. You come home to a chilly house and crank the thermostat, only to hear a ghostly echo of your Nan’s voice: “You’ll spend a fortune heating it from cold! Just leave it on low, love, it’s cheaper in the long run.”
It feels right, doesn’t it? The logic seems sound. A boiler, roaring into life to tackle a freezing house, must surely use more gas than one just gently ticking over, keeping the chill at bay. It’s like keeping a big pot of stew on a low simmer versus letting it go cold and having to blast it back to life.
For decades, this has been the conventional wisdom. But I’m here, as your friendly neighbourhood tech expert, to tell you that for most of us in 2024… Nan was wrong. (Sorry, Nan!)
Let's unpack this myth, shall we?
A Trip Down Memory Lane: Why Your Nan Wasn’t Barmy
Now, before you ring your grandmother to tell her she’s been dishing out duff advice, hold your horses. She wasn’t wrong for her time. In fact, for the house she likely grew up in, her logic was spot on.
Picture a typical post-war British home. We’re talking:
- Single-glazed windows with beautiful, icy patterns on the inside.
- Uninsulated cavity walls that let heat escape faster than a politician breaks a promise.
- Draughty floorboards and letterboxes that created their own indoor microclimate.
- Lofts with just a whisper of insulation, if any at all.
These houses were, to put it technically, leaky buckets for heat. As soon as you put warmth in, it would seep out through the walls, windows, and roof. Letting the house get properly cold meant the very bricks and mortar got cold. This is what engineers call high ‘thermal mass’. To heat that all back up again took a colossal amount of energy and a very, very long time.
On top of that, the heating systems were different beasts entirely. Many relied on old, inefficient boilers or even coal fires that were a right faff to get going. The radiators were huge, cast-iron things that took an age to get warm. The "reheat penalty" wasn't just a number on a bill; it was hours spent shivering under a blanket, waiting for the house to feel vaguely habitable again.
In that world, keeping the heating on a low, constant tick-over was the only sensible strategy. It kept the damp at bay and stopped the house from descending into an arctic tundra that would take half a day to recover from.
The Truth: Your House Isn’t a Leaky Bucket Anymore
So, what’s changed? Well, pretty much everything. Your modern home (anything built or renovated in the last 20-30 years) isn’t a leaky bucket. It’s much more like a Thermos flask.
Thanks to building regulations and a general desire not to live in a fridge, most of us now have:
- Double (or even triple) glazing
- Cavity wall and loft insulation
- Draught-proofing
- Modern, A-rated condensing boilers
This is where the science bit comes in, but I’ll keep it simple. The fundamental principle at play is that heat flows from a warm place to a cold place. The speed of that flow depends on how big the temperature difference is.
Think of it like this: if you make a piping hot cuppa and take it outside on a frosty morning, it will lose heat incredibly fast. If you take a lukewarm cuppa out, it will still cool down, but much more slowly.
Your house is the cuppa. The outside is the frosty morning.
If it's 5°C outside and you leave your heating on all day to maintain 16°C inside, you are constantly maintaining an 11°C temperature difference. All day long, for hours on end, heat is steadily leaking from your home into the cold air outside. You are constantly paying to replace that escaping heat.
But if you turn the heating off when you go to work, the house might cool down to, say, 12°C. For most of the day, the temperature difference is much smaller (only 7°C), meaning you lose heat far more slowly. When you get home, your boiler will fire up to bring it back to a cosy 20°C. Yes, it will work hard for a bit, but the total energy used for that short, sharp blast is almost always less than the energy you would have wasted through constant heat loss all day.
Your modern, insulated home holds onto its heat so much better. The ‘reheat penalty’ is now tiny – often just 30-60 minutes of the boiler being on. That’s a massive saving compared to paying to heat an empty house for eight hours.
The Verdict: Programme, Insulate, and Save
So, for the vast majority of UK homes with a gas boiler and decent insulation, the verdict is in and the myth is well and truly BUSTED.
It is cheaper to set your heating to turn on only when you need it.
Of course, there are a couple of small exceptions. If you live in an old, draughty, uninsulated property that genuinely feels like a historic monument, you might find the reheat time is still significant. But honestly, the best investment there isn’t a new heating schedule; it’s insulation and draught-proofing.
The other exception can be homes with wet underfloor heating laid in a concrete screed. These systems are incredibly slow to react – they’re more like a gentle giant than a nimble sprinter. For them, it can be more efficient to use a lower ‘setback’ temperature (say, 16°C) overnight rather than turning them off completely, as reheating a huge slab of concrete from scratch every morning would take hours.
Tod’s Top Tips for a Toasty, Thrifty Winter
Forget the folk wisdom. Here’s what actually works:
- Become a Programmer: This is your number one weapon. Use your thermostat’s timer. Set the heating to come on 30 minutes before you get up and switch off when you leave. Set it to come on again 30 minutes before you get home and switch off when you go to bed. Heating an empty house or a sleeping family is just burning money.
- Zone Your Home with TRVs: Those little numbered dials on your radiators are Thermostatic Radiator Valves. Use them! Turn the radiator off in the spare room you never use. Set the bedroom radiators to a lower setting (around 18°C is perfect for sleeping) and your living room to a comfortable 20-21°C. Why heat the whole house when you’re only using one room?
- The 1°C Challenge: According to the Energy Saving Trust, turning your main thermostat down by just one degree can cut your bills by up to 10%. Give it a try; you probably won’t even feel the difference, but your bank balance certainly will.
- Insulation is King: I can’t say it enough. The cheapest energy is the energy you don’t use. Topping up your loft insulation and getting cavity walls filled is the single best investment you can make to lower your heating bills forever.
So there we have it. The great British heating debate is settled. It’s time to embrace the timer, get clever with your controls, and give your wallet a well-deserved rest this winter.
Got questions about which smart thermostat is right for you, or wondering if it's time for a more efficient boiler? You know where I am.
Chat with me at tod.ai and let's find the perfect tech for your home.
