By Mick O'Brien · carpenter & builder · sheds-to-homes, cabins and things that stay up in a storm
“I lost a winter night's worth of heat through my shed's single-glazed window, costing me three days of extra firewood before I finally fitted heavy thermal curtains.”
— Mick. It'll still be standing in fifty years.
ArticlesCalculatorsSite PlannerShopLook, if you're off-grid in Australia, windows are your biggest energy leak. Thermal curtains aren't a luxury—they're basic survival. Here's the raw deal.
Look, if you're off-grid in Australia, windows are your biggest energy leak. Thermal curtains aren't a luxury—they're basic survival. Here's the raw deal.
Forget wall insulation R-values. Thermal curtains don't have a standard R-value like fibro. What matters is how much they reduce heat transfer. Good ones add R0.5–R1.0. That's massive for windows—your biggest weak point. Cheap curtains ($20 from Kmart)? Worthless. They'll let heat in/out like a sieve. Proper thermal curtains (with aluminium-backed lining) cut heat loss by 10-20%. In winter, that's less wood or solar power needed. In summer, less fridge running. Simple.
Most people mess this up. Here's the fix:
If you just hang curtains on the frame? You're wasting money. Do it properly or skip it.
Automated curtains (via smart home systems) are a waste of off-grid power. They need constant solar input to run. If your system is small, you'll drain your batteries faster than they save you. Manual is cheaper, more reliable, and needs zero power. Only get automation if you've got a massive solar setup and want to show off. For 99% of off-grid Aussies? Manual. Done.
Practical Tip: Make your own. Buy thermal lining fabric ($15–$25 from Bunnings) and sew it into curtains. Costs $20–$50 for a pair. Better than $80 store-bought. No sewing machine? Use fabric glue. Works fine.
Bunnings: "Thermal Liner Fabric" (aluminium-backed). $18–$25 per roll (covers 1–2 windows). Buy it. It's the only reliable cheap option. Link
Amazon Australia: "Lifted Thermal Curtains" (double-layer). $55–$75 for a pair. Check reviews—avoid "thermal" curtains without aluminium lining. Link
Local Curtain Shops: Custom-made. $120–$200 for a pair. Only worth it if you've got a big window and want it perfect. Otherwise, skip.
Bottom line: Thermal curtains are the cheapest, easiest off-grid win. Spend $20, do it right, and you'll save more power than you think. Don't overcomplicate it. Get the liner from Bunnings, hang it properly, and move on. Your battery bank will thank you.
Worth a watch: Energy efficient window coverings: the best ways to keep the heat in your home · Region
While many off-grid projects are achievable as DIY, certain situations require licensed professionals:
Always check local regulations and obtain necessary permits before commencing work.