Just after midday on a Thursday, construction is well under way on a substantial house in a cul-de-sac in the upmarket Los Angeles neighbourhood of Brentwood. The previous morning, the ground floor was finished, and by the end of day two, the rest of the house will be almost complete. If it sounds like a marvel of engineering, it is. In what appears to be a growing trend, homes are being built off-site (in this case a factory outside Los Angeles), wrapped in white plastic, strapped onto huge trucks and then transported to already-prepared lots by towering cranes. There are no jackhammers or piledrivers, no incensed neighbours awoken at 7am by ear-splitting drilling next door. The really noisy, inconvenient work is done far away. It makes the whole process of home-building almost civilised. They're no ordinary homes. They are kit-set dwellings manufactured by LivingHomes, a Los Angeles-based company that specialises in building modular homes that are also environmentally sustainable and ecologically friendly. The house in Brentwood, which will have been completed by the time you read this, takes up 377 square metres over two levels. Designed by Ray Kappe, it's sleek and sophisticated, despite the fact it is a green house. It has five bedrooms and four bathrooms, a hi-tech hobby room-cum-home office, a media room, a games room and a children's space. A two-storey interior atrium allows generous shafts of light through, the effects of which are enhanced by copious amounts of glass around the house. Inside and out, the place is a tribute to sustainable design and living, which is the core objective of LivingHomes. A solar power system, which includes all-black solar panels, will significantly reduce energy usage. The counter tops in the bathrooms are made from recycled glass. The washer/dryer system uses less water and energy and is far more environmentally friendly than its standard counterparts. The windows and doors are made from recycled glass and aluminium, and much of the wood is reclaimed redwood from a company called Pacific Heritage Wood, which mills materials from old military barracks. Even when the house on the site was torn down to make way for the new home, the dismantled old house was sent to charitable organisation Habitat for Humanity and to Mexico, where it will be used to build homes for the poor. Wired magazine is a partner in the project, installing a home-automation system that controls the home theatre, lighting, temperature and security online - a boon if you realise after you've gone out for the night that you've left the lights on. There's even an iris recognition system, which is about as futuristic as these things get. The games room will be outfitted with surround sound, gaming consoles and special chairs, and a wireless, solar-powered weather station will let the home's inhabitants and visitors know how to dress the next day. According to Steve Glenn, the founder and chief executive of LivingHomes who lives in a similar techie/greenie space in Santa Monica, the house will be worth about US$4.2 million when it's done, including all the hi-tech fittings and contraptions, which seems almost a steal by Hong Kong standards. Yet the construction costs alone are about US$3,000 per square metre, although that doesn't include transporting the modules across town, the installation or the engineering required to prepare the site. But because Glenn wants the concept of green-leaning prefabricated homes to become more a part of mainstream residential construction, costs will be lower. 'We are making it more affordable, and with all the new technologies coming up, things will be much less expensive,' says Glenn, who has been courting interest in the LivingHomes concept from South Africa, mainland China, Israel, Russia and many European countries. The Brentwood house is only the second LivingHomes dwelling in the Los Angeles area (Glenn's being the first) but there are 13 more under construction for other parts of California and one for Hawaii. There are also two LivingHomes communities planned, one in the desert area of Joshua Tree, 225km east of Los Angeles. As more people become attuned to global warming and other environmental issues, ecologically friendly homes can be expected to become increasingly common. 'People are interested in both the modular aspect of this and the green element of it,' says Glenn. In his own home, which was also designed by Kappe, the tiles in the kitchen and bathrooms are made from recycled glass and porcelain. The LED light bulbs used throughout the space, including in Glenn's hand-blown crystal lamps, use only a fraction of the power of standard bulbs. High-performance insulation means that the home stays warm when the weather is cool and remains comfortable at the height of summer. The taps and plumbing are low-flow, including the shower head and toilet flushes. And a smart 'grey' water recycling system means that all run-off from showers, laundry or dish-washing is used to irrigate the greenery around the house (although the fact that Glenn used native plants and trees that are resistant to drought helps to cut water consumption). Another system also helps to harvest rainwater, which is reused for other domestic needs. Counter tops are fashioned from recycled newspapers and cellulose, and paints are non-toxic, free of preservatives and fungicides. Environmentally friendly living, it seems, has just got a lot easier and more stylish. Now there's a positive kind of green house effect.