Decarbonising Buildings Part 2: The smart technology actually worth your attention
Passive House gets a lot of the attention when it comes to energy-efficient buildings — and rightly so. It's the gold standard. But for most of us, living in a certified Passive House isn't happening next Tuesday. We're in existing homes, or buildings that are better than they were but not yet where we want them to be. So what do you do in the meantime?
You use the tools available to you right now. And a handful of smart technologies are genuinely worth your attention — not because they're trendy, but because they reduce real energy waste and give you actual visibility into how your home is performing.
This isn't a pitch for buying more stuff. It's about being strategic with a small number of devices that earn their place.
Smart thermostats
A standard thermostat does one thing: it switches heating on when the temperature drops below a set point and off when it hits the target. That's it. It has no idea whether you're home, whether it's a sunny day, or whether you've left for a two-week holiday.
A smart thermostat learns your patterns, responds to your actual presence, and can factor in weather forecasts to pre-condition your home more efficiently. The result is that you're not heating an empty house, not blasting the heat to catch up after it's dropped too far, and not manually adjusting things every time your schedule changes.
The energy savings vary depending on your existing system and habits, but the concept is sound: precision beats blunt force every time. And in a well-insulated home — even one that's not quite Passive House — a smart thermostat amplifies the performance of what you've already got.
Energy monitoring systems
You can't manage what you can't measure. That's a cliché, but it's earned its place in the language because it's true.
Whole-home energy monitoring systems attach to your switchboard and track consumption circuit by circuit — so you can see not just how much energy your home is using, but where it's going. The hot water cylinder running all night. The old chest freezer in the garage that's pulling more power than everything else combined. The heat pump that's working twice as hard as it should be because the filter hasn't been cleaned in three years.
These systems make the invisible visible. And once you can see it, you tend to do something about it.
Some systems also monitor CO₂ levels, which is genuinely useful. High CO₂ indoors is a reliable indicator that ventilation is inadequate — and poor ventilation is one of the leading causes of moisture problems, mould, and poor indoor air quality. Having a device that tells you when to open a window (or alerts you that your ventilation system isn't keeping up) is more useful than most people realise.
Smart energy meters
If your energy retailer offers a smart meter, get one. They replace the old spinning-dial meters with real-time, granular data on your consumption — broken down by time of day, which matters more than it used to now that time-of-use electricity pricing is becoming more common.
Knowing that running your dishwasher at 11pm instead of 6pm saves you money is useful. But more importantly, smart meters reveal patterns that are hard to spot otherwise — the baseline load that never drops to zero, the overnight spike that doesn't make sense, the appliance that's drawing power even when you think it's off.
| Smart thermostat High value | Reduces heating waste through scheduling and presence detection. Best in already well-insulated homes. |
| Energy monitor High value | Shows you exactly where energy is being used. CO₂ monitoring is a useful bonus for air quality. |
| Smart meter High value | Free through your retailer in most cases. Granular data, time-of-use insights, identifies phantom loads. |
| Smart lighting Moderate value | Useful for habit change and automation, but lighting is rarely the biggest energy load in a home. Don't start here. |
| Smart appliances Context-dependent | Worth considering at replacement time. Not worth replacing functioning appliances early for the smart features alone. |
What smart technology can't do
Here's the honest bit: smart technology is a multiplier, not a fix. It makes a good building perform better. It does not make a leaky, poorly insulated building suddenly efficient.
If your home is losing heat through the walls, roof, and windows, no thermostat — however smart — is going to solve that. The data from your energy monitor might tell you things are bad, but the fix is in the building fabric, not the app on your phone.
That's not a reason to dismiss smart technology. It's a reason to be clear-eyed about what it does. Used alongside a well-considered building upgrade strategy, these tools genuinely help. Used as a substitute for addressing fundamental performance issues, they're an expensive distraction.
Part 3 looks at renewable energy, on-site generation, and how to think about solar in the context of a broader decarbonisation strategy.
