Homes in Japan are usually cheaply built to last about 35 years — before being demolished and replaced. It's a concept that burdens the environment through high-energy consumption due to poor insulation as well as large amounts of wasted, often ecologically concerning, building materials. Yet, recently voices for a more sustainable concept of building have been growing louder. In April 2014, the Japanese Cabinet approved an energy policy that stipulates that all newly built houses have to be zero-energy by 2030, meaning they consume less energy than they produce on a net annual basis by creating and conserving renewable energy. But Japan is still a long way from your average home builder or architect understanding how to increase the sustainability of your home. 

We compiled a list of builders that specialise in eco-homes and resources to turn to for making your home environmentally sound. While the initial cost of an eco-home is often 10-20% higher than that of a run-of-the-mill detached house, it will save you energy bills for years to come, plus government subsidies are available for some renewable energy technologies.

Energy-producing and energy-saving systems

Triple pane, gas-filled windows are a simple yet effective way to increase the energy efficiency of your home. They are the standard in Central Europe by now and widely available in Japan. 

Even the most passive house will still need some energy input. Solar panels on the roof are a well-established option and providers in Japan are plentiful. A set of solar panels can often make a home energy positive, i.e. it will produce more energy than it consumes. 

A lesser-known system to Westerners are Ene-Farms, which stands for energy farms: hydrogen-based generators about the size of a standard refrigerator. They generate electricity by way of natural gas from which the Ene-Farm extracts hydrogen and mixes it with oxygen sourced from the air. The generated electricity can be utilised for all standard household appliances as regular AC current and the heat generated as a by-product is used to heat water up to 60°C. On average, one farm can supply 40-60% of the electricity for an average household. The units are expensive to purchase and install, upwards of US $15,000, but the government offers a subsidy to cover almost 20% of the initial cost.

Traditional techniques

The idea of sustainable housing usually evokes images of futuristic energy management systems and solar panels. Yet there are also long-established Japanese building techniques that focus on sustainability by utilising natural materials that won’t harm the environment or preserving energy. Read our introduction to Japan’s traditional ways of building a home that doesn’t cost the earth through tatami insulation, using yakisugi (Japanese wood preservation), Shikkui lime plastering and tsugite (wood joinery).

Passive houses

A passive house is a home built following standards that promote energy efficiency and comfort while retaining affordability. The goal is to use 1/10 of the energy consumed by a conventional home and to create a comfortable and even climate inside the building — a luxury that most standard Japanese homes lack. Mainly driven by the Passive House Institute in Germany, these environmentally friendly and modern homes are increasingly popular all across the globe.

Kevin Meyerson, a long-term resident of Japan owns a certified passive house in Karuizawa, Nagano Prefecture that was long ranked as the most energy-efficient house in Japan before more modern versions popped up across the islands. 

If you are interested in building a passive house, turn to Passive House Japan, an organisation that has trained and certified hundreds of architects in Japan to follow the stringent standards of the German flagship. The website is in Japanese only, but they can put you in touch with architects that can plan your sustainable dream home.

Off-the-rack green homes

MUJI house

The popular Japanese home brand MUJI has been offering simple and sustainable homes in Japan since 2004. Currently, three models are offered: the Wood House, the Window House, and the Vertical House.

The Wood House is based on the one-room house by architect Kazuhiko Namba, who created the concept it in 1995 as a rudimentary box with high space and utility efficiency. As such, it offers one big open space that is editable by the owners according to their needs.

The Window House is a continuation of the Wood House that was developed by star architect Kengo Kuma.

The Vertical House is the most recent addition to fill the need for buildings that can optimise the lack of space in central Tokyo and fit into the narrowest plots of land, also known as eel’s nests. The models cover floor areas ranging from 90 to 130 sq m. The houses are equipped with double insulation consisting of indoor insulation and an exterior shield, that also incorporates triple pane windows.

Based on the passive house concept, MUJI’s specialists evaluate the plot of land before designing and building the house to determine the building’s angle, number, size and location of windows, as well as where to plant trees, in order to optimise sunlight for both lighting and temperature and the natural breeze.

Daiwa House Group

This Japanese home builder offers two series of single-family houses that take sustainability into account: 1) smart houses called SMAxECO, and 2) xevo, houses that come with an external heat insulating wall.

SMAxECO Houses are equipped with solar panels and lithium ion batteries, which store the generated electricity. The house also comes with Daiwa’s own Home Energy Management System (HEMS), which allows residents to control their energy consumption and air conditioning use through an app. By enabling homeowners to monitor and visualize their energy consumption and potential monetary savings, the company believes that technology help reduce consumption by about 70% compared to conventional Japanese homes.

Xevo houses offer superior insulation, can be equipped with Daiwa’s own solar panel system and follow passive house principles.

Sekisui House

Sekisui House is one of Japan’s largest home builders and its Green First ZERO houses aim for energy self-sufficiency without sacrificing comfort, even to the point of zero external energy consumption. This is achieved by reducing household energy use by about 50%
through heat insulation, energy-efficient LED lights, floor heating and air conditioning, and a HEMS — and by generating the remaining 50% of electricity through solar panels and an Ene-Farm. The energy is stored in a storage cell and an EV outlet for electric cars completes the set-up.

From aiming for zero energy consumption to using natural building materials, planning your sustainable home in Japan can take many directions and looking into resources from both the past and the future will help you to create the perfect home for you and the globe.

By Mareike Dornhege

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