Ms Le Couteur is tabling a private member's motion on Wednesday calling for adequate solar access, external shading, and cross-ventilation to be a requirement for developers in the planning act.

Mary Van de Graaff, who lives in the 2013-built Sentinel apartments in Belconnen, is forced to live in darkness with her husband due to the heat, she says. Despite having two sets of blinds on their ceiling-to-floor length windows, their main bedroom reaches 37 degrees during the summer.

"We downsized and we thought this would be our final move. My husband is 81 and I'm 77 and we're lucky to be able to pay our electricity bill but it does put a strain on us," Mrs Van de Graaff said.

"We have two air conditioners, which cool the living area, but don't reach around the corner to the bedroom. Even having them at 20 degrees and the highest possible speed, we've had to buy two water evaporators."

Mrs Van de Graaff has put solar film on her unglazed western-facing windows, which has helped "a bit" with the heat, but her balcony's tiles heat up like a "blow torch" that seeps through, she said.

"The body corporate doesn't allow you to change the facade [to add external shade]. To move ... is just so expensive. And where would you move to? Everywhere is the same."

The Sentinel owners' incooperation had rejected a proposal to put louvres on west-facing units for two years, chairman Alastair Wilson said. The louvres would be unlikely to withstand strong winds and it would be too difficult to get approval from all the unit owners involved, noting the cost.

"Aesthetics of the building would be seriously affected if only one or two balconies had such attachments," Mr Wilson said.

Ms Le Couteur's motion was pointing to changes along these lines that could make a big difference for apartment owners, she said.

Some solutions to unbearable apartment heat could be having windows that weren't ceiling-to-floor length and could be wound open wider than 20 centimetres. Energy efficient cooling should also be required for the territory's public housing.

Current planning guidelines were mostly based around preparing for Canberra's colder months, Ms Le Couteur said. The energy efficiency rating system - which the government is reviewing - was also based on this. Sentinel building had a rating of five stars out of 10, which was considered very high.

"Canberra, from an energy efficiency point of view, is counted as a cold climate, which kind of makes sense, but what that means is that they don't even bother rating the performance when its for the hot weather in Canberra," Ms Le Couteur said.

"Basically, we need to start recognising that the weather is getting hotter, the summers are getting hotter, and we need to actually have external shading and a plan for summer - not just winter."

It was up to the government, particularly the Environment, Planning and Sustainable Development Directorate, to act on her motion and implement changes, Ms Le Couteur said, as she didn't have the resources.

The directorate was contacted for comment.

A petition calling for the planting of more than 7000 trees a year in the territory was tabled by Ms Le Couteur on Tuesday. Street and park trees in the national capital's established suburbs are declining by about 3000 a year.