10 Innovative, Energy-efficient Building Materials

Key Insights

The pursuit of energy-efficient construction ultimately revolves around achieving a tight envelope. In construction terminology, the more effectively a building blocks out wind and rain, the tighter its envelope is considered.

Achieving a tight envelope using renewable and recycled materials is an even better outcome. While many energy-efficient products are introduced annually, some builders hesitate to adopt them due to the higher upfront costs. In fact, adding a layer of insulation or installing specially coated windows can raise material costs by 20 to 30 percent.

However, energy conservation experts typically argue that investing in more efficient materials results in lower heating and cooling costs, ultimately allowing homeowners to recover their investment within just a few years.

Let's explore some of the most recent energy-efficient building materials available today.

10: Recycled Steel

If you take a look at the materials from the Steel Recycling Institute (SRI), you might just consider skipping traditional wood beams when planning your next home construction.

According to the SRI, builders are simplifying the framing process by ordering steel beams and panels that are custom-made to match each design. The SRI highlights steel's resilience, especially in areas prone to high winds and earthquakes. Additionally, they note that while constructing a 2,000-square-foot (186-square-meter) house typically requires 40 or 50 trees, using recycled steel only demands the equivalent material from six scrap cars [source: Steel Recycling Institute].

Each year, at least 65 tons (59 metric tons) of scrap steel are recycled. This process not only cuts down the energy needed to produce new steel by 75 percent, but it also reduces the strain on landfills [source: Steel Recycling Institute].

9: Insulating Concrete Forms

This technology, which is over 60 years old, has found new relevance thanks to its energy-saving potential.

The Portland Cement Association, a leading producer of concrete forms, describes them as "cast-in-place concrete walls encased by two layers of insulation material." Concrete is poured into these forms, which act as insulation and become an integral part of the structure. This technology is commonly used for freestanding walls and building blocks.

A study funded by the industry and conducted by the Massachusetts Institute of Technology, published in late 2010, found that buildings constructed with insulated concrete forms consumed 20 percent less energy than their wood-frame counterparts in cold climates like Chicago [source: Ochsendorf].

8: Plant-based Polyurethane Rigid Foam

After the leading manufacturer of surfboard material closed down and was fined by the Environmental Protection Agency for using harmful chemicals, a surfboard maker in San Diego began producing foam derived from plant sources.

Ned McMahon, the chief operating officer of Malama Composites, is producing the foam using sustainable materials such as bamboo, hemp, and kelp.

The so-called rigid foam is utilized in a variety of products including insulation, wind turbine blades, furniture, and, naturally, surfboards.

As insulation, this foam provides excellent resistance to moisture and heat, superior acoustics, and protection against mold and pests. It also offers a higher R-value than fiberglass or polystyrene, which means it provides better thermal resistance and superior insulation [source: Malama Composites].

7: Straw Bales

Ever played with LEGOs? If so, you can build a house. This is the mindset of Mark Jensen, who oversees the construction of straw bale houses for Native American communities. Straw, a byproduct of the grain industry, is often discarded or burned otherwise.

The California Straw Building Association reports that straw, when kept dry, can endure for thousands of years. Straw bales bond well with stucco and plaster walls, providing excellent insulation.

Straw bales typically weigh between 50 and 90 pounds (23 to 41 kilograms) each. For a 2,000-square-foot (186-square-meter) house, approximately 300 medium-sized straw bales are needed. Although few building codes specifically cover straw bale construction, local authorities evaluate each case individually [source: NAHB Research Center].

6: Cool Roofing

The Cool Roof Rating Council explains this concept: just as wearing a white T-shirt on a hot day keeps you cooler because it reflects heat rather than absorbs it, a cool roof works the same way. It reflects the sun’s heat, staying cooler and transferring less heat into the building.

In the past, cool roofing required light-colored materials, but recent treatments allow consumers to select darker roofing options that can still reflect heat back into the atmosphere.

Undoubtedly, these materials are pricier than conventional roofing. Eco Home Magazine reported one estimate indicating an extra $80 per square foot. However, experts suggest that the reduction in electricity bills during the sweltering August heat will quickly offset these additional costs.

5: Structural Insulated Panels

Picture an Oreo cookie, and you’ve got the concept of a structural insulated panel (SIP). SIPs consist of a foam insulation core sandwiched between two layers of plywood, strand board, or cement panels.

In 2009, this material accounted for less than 2 percent of new homes being built.

Some estimates suggest that SIPs can reduce energy costs by 50 percent compared to houses constructed with traditional materials [source: NAHB Research Center]. However, some individuals find the appearance unappealing, and architects often have limited experience working with this material.

The National Association of Home Builders states that SIPs are fire resistant and can be used for foundations, floors, basements, and load-bearing walls. As for aesthetic concerns, their research highlights that the surfaces can be finished with wood grain, stucco, or even have siding, bricks, and stone applied to the panels.

4: Recycled Wood/Plastic Composite Lumber

Ever wondered where all those plastic bags end up? If you’ve recycled them, they could be part of the construction of your next deck or even used in a nearby playground.

The National Association of Home Builders reports that this blend of wood fibers and recycled plastics is more durable and less toxic than traditional treated lumber. The material also offers greater rigidity than pure plastic lumber due to the additional strength provided by the wood fibers.

Composite lumber is more resistant to mold and rot, but it becomes stiffer in cold weather and more flexible in hot temperatures compared to plastic lumber. However, it comes with a significantly higher price tag than traditional treated lumber.

3: Low-E Windows

The "E" in Low-E stands for emissivity, referring to the special metallic oxide coating on these windows that keeps warmth inside the home during the winter and prevents heat from entering during the summer.

This metallic coating is often applied to external storm windows in homes lacking double-pane windows. There are two types of coatings: soft coatings, which are placed between layers of glass, and hard coatings, which are applied to the outer surface.

Low-E windows typically range in price from $60 to $110 each. While they cost 10 to 15 percent more than standard clear glass storm windows, they offer significant advantages: they can reduce heat transfer through the glass by up to 50 percent, leading to a reduction in heating costs of 10 to 20 percent [source: NAHB Research Center].

2: Vacuum Insulation Panel

A 1-inch (2.54-centimeter) Vacuum Insulation Panel (VIP) offers up to seven times the insulating power of traditional insulation products [source: NAHB Research Center]. While it holds promise as an ideal insulation solution, it is currently only used for commercial refrigeration and specialized container applications.

The VIP has the look of something straight out of old NASA space technology footage: it's a textured silver rectangle containing a core panel sealed in an airtight envelope. These panels can be manufactured in various sizes.

The National Association of Home Builders notes that the primary challenge with the VIP is its delicate surface, which requires a protective cover. The association is collaborating with Dow Chemical, the leading producer of the panels, to make them available as insulation for attics in upcoming residential buildings.

1: Earth

One of the main benefits of using rammed earth or adobe walls is the material's abundance, low cost, and the fact that it doesn't need to be transported to the construction site. However, finding skilled craftsmen experienced in working with earth can be a significant challenge.

Although countries like China, Peru, and New Zealand have included this form of construction in their building codes, the U.S. has not followed suit. The difficulty in finding qualified labor has led the National Association of Home Builders to estimate labor costs at no less than $80 per square foot.

Despite these challenges, the National Association of Home Builders highlights the excellent thermal mass properties of earthen walls, and the fact that the material is sourced from renewable resources makes it an attractive option.