AGEO, Saitama Prefecture—More municipalities in Saitama Prefecture are subsidizing house renovation work for thermal insulation, an improvement that not only lowers utility bills but can also save lives, industry sources said.

The costs for thermic renovation, which can help maintain comfortable room temperatures in summertime and wintertime, vary depending largely on the size of the residence. Expenses for the work at spacious homes can reach millions of yen.

By tapping into public funds to cover part of the costs, local authorities hope more households will introduce heat insulation.

The city government of Ageo in the prefecture plans to start offering a maximum subsidy of 100,000 yen ($638) for thermic renovation work later this fiscal year.

Similar measures have been introduced elsewhere in the prefecture, including Kumagaya, Kawaguchi and Okegawa.

The central government also has programs to subsidize thermal renovation work on doors, walls, windows and other sections of houses. The program for windows, for example, grants subsidies of up to 2 million yen per house.

Ageo city authorities in May signed an agreement of cooperation with Saitama Dannetsu Kaishu Kaigi (Saitama thermal renovation council), a private group of volunteers that promotes thermic renovation of houses.

The group organizes 24 companies based both in and outside Saitama Prefecture, including building contractors, architectural design firms and manufacturers of construction materials.

Founded in 2019, the council has been conducting awareness campaigns and research on heat isolation.

An infrastructure ministry survey shows that only 18 percent of all houses in Japan meet existing standards on thermal insulation specifications. The remaining 80 percent or so have insufficient performances in heat insulation.

And 24 percent of all houses are not thermally insulated at all.

Heating tends to be expensive in thermally uninsulated houses, which may also suffer from air leakage.

Warmed air does not readily permeate an entire residence, leaving certain sections, particularly dressing rooms, at seriously low temperatures.

Gaps in room temperatures can cause sudden changes in blood pressure, raising the risk of cardiovascular disorders known as “heat shocks” in Japan, officials said.

“Some 17,000 people die annually from heat shocks, as opposed to the yearly death toll of about 2,600 from traffic accidents,” said Masayuki Mae, adviser to the Saitama thermal renovation council, during a signing ceremony for the agreement with the Ageo city government. “Top priority should therefore be given to raising temperatures in houses.”

Mae, an associate professor of architectural environment engineering with the University of Tokyo graduate school, simulated heat insulation effects and heating expenses in a hypothetical two-story house with a total floor area of about 120 square meters.

The sensory temperatures, as felt by humans, averaged 15.8 degrees across the entire unrenovated building in winter with an outside air temperature of 4.8 degrees. Annual expenses to heat the building were estimated at 71,000 yen.

After thermal insulation work, including double-glazing the downstairs windows, the mean sensory temperature rose to 16.4 degrees while annual heating expenses dropped to 54,000 yen.

 Additional work, such as covering the downstairs floor with heat-insulating materials, resulted in an average wintertime sensory temperature of 16.8 degrees, and heating costs of 46,000 yen.

Renovating all windows, the downstairs floors, the upstairs ceiling and all external walls led to a mean sensory temperature of 19.2 degrees and lowered the heating expenses to only 33,000 yen, according to the study.

Thermic renovation is also known to improve efficiency of summertime air-cooling.

In 2022, the Saitama thermal renovation council worked on an elementary school building in Saitama city, including applying heat-insulating materials on the ceiling.

The sensory temperatures on the top floor fell by around 5 degrees, officials said.

“Expertise is required for the sort of work that will never fail to have an impact,” said Yoshio Sato, the council’s chairman, who operates a building contractor in Ageo. “You can choose to continue living in your house while work goes on, so I really hope people will consider this option of thermally renovating their homes for the comfort of their lives.”