Governments are rushing to encourage construction of many more apartments, to manage shortages of rental properties and associated high prices. I am not at all sure that a simplistic focus on supply will manage the exploitation and market failures associated with housing, but I will put that aside for this article.
Many recently built high rise apartments are nightmares to live in. They are solar ovens whenever exposed to sun.
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They are poorly ventilated, so when people dry clothes indoors (because they are not allowed to dry clothes on balconies) mould and damage to building materials occur.
Lack of cross-ventilation limits the effectiveness of natural ventilation, and outdoor noise may deter occupants from opening windows anyway. Noise transfer between apartments can be a problem.
Concrete hot balconies
More subtle is the problem of thermal bridging.
Concrete is a good conductor of heat, so sun shining on dark paved balconies flows into the apartment through the continuous concrete slab, adding to overheating.
Metal frames on windows
The balcony paving also re-radiates heat in through the glazing. In winter, the balcony acts like a fin, sucking heat out of the apartment. Metal window frames transfer surprising amounts of heat. If painted a dark colour, summer heat gain is even worse.
Dark coloured blinds
Then there are the dark coloured blinds, specified by many designers and required by owners corporations “for consistency”.
These are solar collectors – potentially useful in winter, but a disaster for much of the year. Dark coloured walls add to summer problems. External shading is often simply not allowed.
It’s not hard to get it right
It’s relatively easy to achieve a high energy rating to comply with building codes in most apartments. Ceilings, floors and most walls are shared with other apartments, so heat flows are limited to a few windows and small areas of walls. Limited ventilation means they score well on air leakage.
Central hot water and energy systems
Central hot water, space heating and cooling systems are often very inefficient and difficult to control – and costly to run, often with high fixed charges. Embedded electricity networks also offer opportunity to charge higher energy prices.
And there is limited scope to install solar, or to cost-effectively share solar output between apartments.
Then there are the problems linked to poor quality construction: water leaks, condensation within walls, cracks and flammable cladding. A recent book by David Oswald and Trivess Moore (Constructing a Consumer-focused Industry) outlines the problems, which are world-wide, not just in Australia.
One study presented two case studies of high-rise apartment buildings.
Note the large contribution of water heating to overall energy use.
While cooling was a small factor, it may be that the case study buildings did not have central cooling.
In any case, the significance of solar gain driving extreme temperatures in apartments exposed to sun is a health, safety, amenity and resilience issue, not necessarily just an energy cost.
And many tenants may not be home during times of extreme conditions.
We need to do so much better
We need to better understand the complexities of apartment design and performance before we add to the already substantial stock of poor buildings.
We must also work out what is wrong with existing buildings and devise strategies to fix them quickly and at an affordable costs for owners and tenants.