Do shutters actually lower your power bill in winter?

Yes. Properly fitted shutters create a seal against the window frame that can reduce heat loss through the glass by more than 50%, which shows up as a real difference on your winter power bill - though exactly how much depends on your windows, orientation and how well they're fitted.

Whether it's a place in Tauranga or one of the older villas I've been seeing more of over in the Waikato, I get a lot of calls this time of year asking the same thing: will shutters actually make a difference to my heating costs, or is that just a sales line?

Fair question. So here's the honest answer, from someone who's fitted a lot of windows around the Bay.

Glass is one of the biggest weak points in any home's insulation. Even double glazing loses heat far faster than an insulated wall. What a well-fitted shutter does is add a second barrier right against the frame - a still layer of air between your room and the glass. That still air is the insulation. It's the same principle as a good jacket: it's not the fabric that keeps you warm, it's the air it traps.

The studies I've seen put the reduction in heat loss through a shuttered window at over 50%, depending on the fit and the glazing behind it. That's not a marginal difference. Over a winter, in a room you actually use - a lounge, a bedroom, a home office - that adds up to a heater working less hard, less often.

A few things matter for getting that result:

• Fit is everything. A loose or off-the-shelf shutter won't seal the same way a made-to-measure one does. Gaps around the frame are exactly where the warmth escapes.

• Closing them at night makes the biggest difference. Open them up during the day to let the sun in, close them once the temperature drops.

• PVC and timber both perform well - the insulation comes from the design and the seal, not the material itself.

I had a client on the Papamoa side last winter who swapped tired curtains for hinged shutters in their main bedroom and said it was the first winter they didn't need a heater running overnight in that room. That's anecdotal, sure, but it lines up with what the numbers say.

If you're weighing up whether shutters are worth it purely on comfort and cost, winter is actually the best time to see it for yourself - book a free measure and quote and I'll talk you through what would work in your home, no pressure either way.