When to open your windows, and why: heatwaves, condensation, mold, humidity — the physics of a cooler, drier home, in plain words.https://openshut.app/enhttps://openshut.app/blog/morning-rule-when-to-shut-windows/https://openshut.app/blog/morning-rule-when-to-shut-windows/On hot days there is one moment when open windows start heating your home. How to spot the crossover and lock the night's coolness inside.Tue, 11 Aug 2026 00:00:00 GMThttps://openshut.app/blog/why-humid-heat-feels-hotter/https://openshut.app/blog/why-humid-heat-feels-hotter/28 °C can feel pleasant or unbearable depending on how much water the air carries. The physics of sweat, and why dew point beats the humidity %.Wed, 29 Jul 2026 00:00:00 GMThttps://openshut.app/blog/building-thermal-inertia-comfort/https://openshut.app/blog/building-thermal-inertia-comfort/Why old stone houses stay cool through July afternoons while modern flats overheat by noon — and how to work with your walls, not against them.Wed, 15 Jul 2026 00:00:00 GMThttps://openshut.app/blog/roof-windows-stack-effect/https://openshut.app/blog/roof-windows-stack-effect/Warm air rises. A roof window turns your home into a gentle chimney that flushes heat out even without wind. How the stack effect works.Wed, 01 Jul 2026 00:00:00 GMThttps://openshut.app/blog/afternoon-dry-air-trap/https://openshut.app/blog/afternoon-dry-air-trap/Afternoon air at 35% humidity often holds more water than morning air at 90%. Why relative humidity tricks you into airing at the worst hour.Tue, 16 Jun 2026 00:00:00 GMThttps://openshut.app/blog/keep-home-cool-heatwave-without-ac/https://openshut.app/blog/keep-home-cool-heatwave-without-ac/A home can stay livable through a heatwave without AC — if the timing is right. Shut and shade by day, flush at night, and watch the humidity.Tue, 02 Jun 2026 00:00:00 GMThttps://openshut.app/blog/shutters-blinds-curtains-block-heat/https://openshut.app/blog/shutters-blinds-curtains-block-heat/Sunlight that passes the glass becomes heat you cannot send back out. Why exterior shutters beat any curtain, and what still helps if you rent.Tue, 19 May 2026 00:00:00 GMThttps://openshut.app/blog/prepare-home-for-summer-checklist/https://openshut.app/blog/prepare-home-for-summer-checklist/The first heatwave is won in May, not in July. A practical checklist — shading, airflow paths, night routine — to prepare your home before the heat.Tue, 05 May 2026 00:00:00 GMThttps://openshut.app/blog/best-bedroom-temperature-for-sleep/https://openshut.app/blog/best-bedroom-temperature-for-sleep/Around 17–19 °C is commonly recommended for sleep, but humidity decides how the night actually feels. How to get your bedroom there without AC.Tue, 21 Apr 2026 00:00:00 GMThttps://openshut.app/blog/cooking-without-steaming-up-home/https://openshut.app/blog/cooking-without-steaming-up-home/Every pot that boils pushes water vapour into your air. Where cooking steam actually goes, and how lids, hoods and smart airing keep your home dry.Tue, 07 Apr 2026 00:00:00 GMThttps://openshut.app/blog/how-much-moisture-home-produces/https://openshut.app/blog/how-much-moisture-home-produces/Breathing, cooking, showers and laundry release litres of water vapour every day. Where it all goes, and why it has to be ventilated out.Tue, 17 Mar 2026 00:00:00 GMThttps://openshut.app/blog/spring-airing-pollen/https://openshut.app/blog/spring-airing-pollen/How to air your home in pollen season: when pollen pressure is lower, and why short cross-draft bursts beat a window left open all day.Tue, 03 Mar 2026 00:00:00 GMThttps://openshut.app/blog/ideal-indoor-humidity/https://openshut.app/blog/ideal-indoor-humidity/The 40–60% indoor humidity rule explained: why the number moves with temperature, and how to steer your home back into the comfort zone.Tue, 17 Feb 2026 00:00:00 GMThttps://openshut.app/blog/bathroom-condensation-shower-steam/https://openshut.app/blog/bathroom-condensation-shower-steam/Why your bathroom fogs up after a shower, and how dew point, door discipline and short intense airing keep condensation and mold away.Tue, 03 Feb 2026 00:00:00 GMThttps://openshut.app/blog/tilted-window-ventilation-myth/https://openshut.app/blog/tilted-window-ventilation-myth/A tilted window swaps far less air than you think. Here is why tilt ventilation fails, what it costs in winter, and what works instead.Tue, 20 Jan 2026 00:00:00 GMThttps://openshut.app/blog/drying-laundry-indoors-without-mold/https://openshut.app/blog/drying-laundry-indoors-without-mold/A load of wet laundry releases litres of water into your air. How to dry clothes indoors without feeding condensation and mold.Tue, 06 Jan 2026 00:00:00 GMThttps://openshut.app/blog/mold-in-bedroom-airing-schedule/https://openshut.app/blog/mold-in-bedroom-airing-schedule/You exhale water all night and cold bedroom walls collect it. A simple morning airing routine that keeps mold out of your bedroom for good.Tue, 16 Dec 2025 00:00:00 GMThttps://openshut.app/blog/does-airing-in-winter-waste-heat/https://openshut.app/blog/does-airing-in-winter-waste-heat/Most of your home's warmth is stored in walls and furniture, not in the air. Why short winter airing costs far less heat than you think.Tue, 02 Dec 2025 00:00:00 GMThttps://openshut.app/blog/stossluften-german-shock-ventilation/https://openshut.app/blog/stossluften-german-shock-ventilation/Shock ventilation swaps stale humid air in 5–10 minutes without cooling your walls. How Stoßlüften works, and why it beats a tilted window.Tue, 18 Nov 2025 00:00:00 GMThttps://openshut.app/blog/condensation-on-windows-causes/https://openshut.app/blog/condensation-on-windows-causes/Window condensation isn't a window problem — it's humid indoor air meeting a surface colder than its dew point. Here's how to stop it.Tue, 04 Nov 2025 00:00:00 GMThttps://openshut.app/blog/magnus-formula-explained/https://openshut.app/blog/magnus-formula-explained/The short formula that turns temperature and relative humidity into real water content — walked through step by step, with one honest example.Tue, 21 Oct 2025 00:00:00 GMThttps://openshut.app/blog/why-home-feels-damp-autumn/https://openshut.app/blog/why-home-feels-damp-autumn/Clammy rooms, misted windows, musty smells: why autumn makes homes feel damp, what is actually happening, and the airing routine that fixes it.Tue, 07 Oct 2025 00:00:00 GMThttps://openshut.app/blog/how-long-should-you-air-a-room/https://openshut.app/blog/how-long-should-you-air-a-room/Five minutes or an hour? How long airing really takes by season and window setup, and why short and wide beats long and timid.Tue, 23 Sep 2025 00:00:00 GMThttps://openshut.app/blog/dew-point-explained/https://openshut.app/blog/dew-point-explained/What the dew point actually measures, why cold surfaces get wet, and how one temperature beats relative humidity for reading the air.Tue, 09 Sep 2025 00:00:00 GMThttps://openshut.app/blog/cross-ventilation-guide/https://openshut.app/blog/cross-ventilation-guide/Why two openings on opposite sides beat one wide-open window, how wind and the stack effect drive the flow, and when a cross-draft helps.Tue, 19 Aug 2025 00:00:00 GMThttps://openshut.app/blog/window-fan-direction/https://openshut.app/blog/window-fan-direction/A window fan pointed the wrong way can heat your home. When to blow in, when to blow out, and how to build a two-window push-pull setup.Tue, 05 Aug 2025 00:00:00 GMThttps://openshut.app/blog/why-bedroom-hot-at-night/https://openshut.app/blog/why-bedroom-hot-at-night/Outside it's cool, inside you're sweating. Your walls stored the day's heat and are giving it back — here's how to break the cycle.Tue, 22 Jul 2025 00:00:00 GMThttps://openshut.app/blog/relative-vs-absolute-humidity/https://openshut.app/blog/relative-vs-absolute-humidity/Relative humidity says how full the air is, not how much water it holds. Why that difference decides the right moment to air your home.Tue, 08 Jul 2025 00:00:00 GMThttps://openshut.app/blog/night-cooling-open-windows-at-night/https://openshut.app/blog/night-cooling-open-windows-at-night/Night airing works, but only if you do it right: real airflow, the right hours, and shutting everything before the morning heat returns.Tue, 24 Jun 2025 00:00:00 GMThttps://openshut.app/blog/should-you-open-windows-during-a-heatwave/https://openshut.app/blog/should-you-open-windows-during-a-heatwave/Opening windows in a heatwave can make your home hotter and damper. Here is the simple two-number rule for when to open and when to shut.Tue, 10 Jun 2025 00:00:00 GMT