Room zoning and floor planning

The payoffWhat zoning is worth

Zoning means arranging a house so its parts can be heated and cooled separately. It's simple, and it works. In detailed modelling of typical UK houses, heating only the occupied rooms cut heating energy by about 20% on average, ranging from 8% to 37%. The biggest savings came when the doors between zones were kept closed and when parts of the house were used only some of the time.

Doors matter as much as the plan. An open doorway lets warm air flow straight into the cold rooms beyond, so a zoned plan only works if the zones can actually be shut.

SizeThe first zoning decision

The cheapest room to heat is one you don't build. In 2020, the average new ACT house was 256 m², the largest of any state or territory, against a national average of 236 m².

The star rating is measured per square metre, so it doesn't penalise size. Every extra square metre still needs heating, cooling, lighting and cleaning. At the same star rating, a 200 m² house needs about 22% less heating and cooling than a 256 m² house. A well-planned smaller house, with rooms that work hard and little corridor, often lives larger than a big one.

GroupingDay, night and occasional rooms

Group rooms by when they're used, and give each group its own place in the plan:

The last two rows are the ones most often missed. A guest wing or rumpus room that opens straight onto the main living area has to be heated whenever the living area is. Give it a door and it costs nothing when it's empty.

Open planOpen when you want it, closed when you need it

Open-plan living is popular for good reason, and it doesn't have to be given up. It needs to be able to close:

• Wide sliding, pocket or glazed doors let a family room open fully onto the kitchen for a party and close off on a cold night. Glazed doors keep the light and the sightlines.
• Open stairs act as chimneys. Warm air rises up the stairwell to the upper floor, and cold air falls back down. A door at the top or bottom of the stair, or a stair enclosed in its own hall, stops a two-storey house heating its upstairs by accident.
• Double-height voids collect warm air at the ceiling, metres above anyone sitting below. If you want one, keep it modest. A ceiling fan running slowly in reverse in winter pushes the warm air back down.

The same stack effect is useful in summer. A stair or void with an openable high window lets hot air escape at night while cool air comes in low, so the house flushes itself out.

BuffersRooms that protect other rooms

Rooms you pass through briefly can shield the rooms you live in:

• The garage, laundry and storage on the west take the afternoon sun so that living rooms and bedrooms don't. On the south, they shelter the house from cold.
• Never put the garage on the north. It takes the best winter sun in the house and gives nothing back.
• An entry airlock, or simply a door between the front entry and the living areas, stops every arrival letting a gust of cold air through the house. A seal on the door from the garage matters just as much. Garages are cold and the door gets used constantly.
• Bathrooms and walk-in robes between bedrooms and a cold south or west wall add another layer between the sleeping zone and the weather.

ServicesMatch the heating to the zones

Zoning only saves energy if the heating can follow it:

• A separate control for each zone. That might be a split system in each zone, or a ducted system with motorised dampers and a thermostat in each zone.
• Heat where people sit. Put the heater or outlet in the room that is used most, not in a hallway.
• Fast or slow. Systems that respond quickly, like reverse-cycle air conditioners and panel heaters, suit rooms used intermittently. Slow systems like in-slab hydronic heating suit rooms that are occupied all day, and can't be turned up and down usefully.

Decide the heating zones at sketch stage, alongside the room layout. Ductwork, pipe runs and indoor units are much easier to plan before the walls are fixed than after.