Eco-friendly homes may be getting cheaper and more stylish, according to recent reports from SmartPlanet.

In Philadelphia, Postgreen Homes is building small utilitarian houses - usually less than 1500 sq. ft. - with a base price of US$355,000. Radiant heat comes through the concrete floors, IKEA cabinets and fixtures use wood certified by the Forest Stewardship Council and in the bathrooms, dual flush toilets conserve water. The company actually built another home for just US$105k. The so-called 100k House Project was recognised by the US Green Building Council as the #1 new home in the US in 2010 for its focus on energy-efficient strategies and streamlined design. Postgreen is still a relatively small company, but despite a tough economy, the company has sold nine houses. And it's planning to build a six-unit co-housing project this year. SmartPlanet features Postgreen in this article, "Rethinking the Row Home".

At US$500k, Simpatico's pre-fab homes in northern California are relatively more expensive, but so too is the region's property market. The company cuts construction time by building customisable modules in a factory, then assembling them onsite. The houses feature solar panels and a passive solar design. A boiler meanwhile heats hot water that is carried through pipes to warm the floors and rooms. The net effect is a home that is almost entirely energy self-sufficient. Check out this video with SmartPlanet's Sumi Das, who tours Simpatico's prototype house.

Do you know of a good example of energy-efficient, eco-friendly architecture? Let us know! Share your comments here.