What are SIPs?
A significant efficiency problem in traditional green building is thermal bridging, which is a term used to describe the wooden frame of a building conducting heat. This happens because insulation is put between the studs in a wall, so the area between them is insulated while the studs themselves cannot be insulated. This phenomenon occurs regardless of insulation levels, as the studs of a frame act as bridges between the two outer surfaces of a wall, hence the term bridging. One solution that's been developed for this problem is the structural insulated panel (SIP), which is comprised of two layers of insulated sheathing surrounding a layer of dense insulation. These panels serve as structural components themselves, and don't require framing, thus eliminating the issue of thermal bridging. They can be used for the entire building envelope, including floors and roofing.
SIPs are considered a green building technology for two main reasons: they allow for energy- efficient construction and they use materials more efficiently than stick-built homes. SIPs allow for such energy-efficient construction because they are very well insulated and allow for more airtight construction than traditional building methods because they are assembled as large panels in an off-site facility rather than being built on-site. It might seem counterintuitive that SIPs use less material than traditional framing. They save building materials by being made to order (at least some of them) and are built in a factory, so that materials can be used with little waste, whereas many board ends are thrown out in traditional framing. This information is supported by a growing body of literature around the use of SIPs to achieve LEED and other building certifications for green construction. In addition to providing energy efficiency, SIPs allow for an efficient construction process that is much faster than that of a conventional stick-built home.
Why You Probably Haven't Heard of Them
If they're so great, why aren't more people using them? There are probably two main reasons for this. First, builders and architects generally stick with what they know. They can't be blamed for doing so, as they have a lot of money and their professional reputations riding on their projects, but this can make it hard for a newer product like SIPs to fit into the market. Secondly, many people have never heard of SIPs, which makes it difficult for them to have a home built out of them because, as mentioned above, architects and builders are less than enthusiastic about adopting the technology. However, SIPs have one thing going for them when it comes to being widely adopted: their efficiency. As building codes become more strict and everyone becomes more concerned with energy efficiency, SIPs are a great choice because they satisfy stringent energy requirements, and do so in a way that's hard for conventional building practices to match.