Tiny Houses—Big Energy Savings with Plastics

Professor Plastics

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Building a Tiny House that’s Big on Energy Efficiency

Question: How big is the average American house?

Answer: Pretty big and getting bigger, hovering around an average 2,700 square feet in 2015. That’s nearly the square footage of a tennis court … the doubles tennis court.

(On my humble professor’s salary, my house feels more like the size of a ping-pong table. Just putting that out there …)

But what about all those charming homes that are part of the wildly popular “tiny house” movement? Aren’t they altering the “McMansionization” of U.S. housing?

Well, not so much yet. But the tiny house movement—typified by houses in the 100 to 400 square feet range—is fueling conversations about the impact of our houses on the environment.

Those are good discussions to have. Among other environmental stressors, our houses and buildings use 41 percent of our nation’s energy, and much of that energy is wasted due to outdated building practices. If the tiny house movement can focus national attention on the need to reduce the environmental footprint of our houses, then that’s a good thing.

That’s one reason why I think that a tiny house built in Boulder, Colo., is so cool. Tiny House Nation star Zack Giffin and builder Paul Baumann partnered with Plastics Make it Possible® to build a tiny house that would showcase how advances in plastic building products can help homeowners—tiny or otherwise—become more energy efficient, while also creating a durable, low maintenance house. (No, I don’t mean that the homeowners are tiny … jeez.)

It all starts with an envelope.

The “building envelope,” that is, a term for the physical barriers that separate the inside conditioned space from the outside unconditioned area. The building envelope provides barriers to heat/cold, air, water, light, and noise. From an energy efficiency standpoint, the barriers to temperature and air are the big ones—the idea is to “seal” the envelope from the outdoors just like an envelope carrying a letter in the mail. And that’s precisely where scores of plastic building products shine.

Let’s look at some of the primary products Zack and Paul used to seal the building envelope and improve energy efficiency:

  • Spray polyurethane foam insulation—this plastic foam insulation expands into the wall cavities to help block unwanted movement of air and heat/cold, plus it helps keep out dust, dirt, and insects.
  • Polyisocyanurate foam board—this stiff plastic foam board was applied to the outside of the tiny house walls (under the siding) to help prevent heat/cold and untreated air from even touching the wall materials/framing, further insulating the house from the weather.
  • Solar power shingles—this relatively new product incorporates energy producing solar cells into the plastic roof shingle itself, so there’s no need for an additional bulky panel on the roof. And of course the shingles provide power from the sun, so the tiny house can potentially even go off the grid, if desired. (I just love that phrase: go off the grid. It sounds so … Bohemian.)
  • Vinyl windows—these windows have plastic frames with multiple chambers to improve the insulating properties, plus they provide tight seals to minimize air leaks.
  • Polyurethane clad front door—this traditional looking plastic coated door with an insulating plastic foam core improves resistance to heat/cold.
  • Vinyl siding and trim—these exterior plastic products are impervious to water, don’t need periodic painting, and provide an additional barrier between indoors and out.
  • Polycarbonate skylight—this tough plastic skylight provides natural daylight, thermal resistance, and UV protection to help save energy. How tough is it? Well, it may not actually be as tough as “bullet-proof” glass, it’s made from the same material: polycarbonate.

The house is full of additional plastic building products, such as easy to maintain, comfortable luxury vinyl tile, plastic composite counter tops, and plastic bead board wall coverings.

Why focus on plastic building products in a tiny house? In addition to the energy saving benefits noted above, the builders point out that many of these tiny houses are mounted on trailers to make them mobile, so tough, durable building products make sense.

In addition, one of the biggest house destroyers is water, so incorporating building materials made with durable plastics that are impervious to water can help limit damage. For example, plastic foam insulation reduces the concern over the huge loss in R-value that can result when some types of insulation get wet and mat together. And house wrap and caulks and sealants help reduce the potential for damage caused by water leaks that can lead to rotted wood.

So plastics contribute to increased durability of the house as a whole and can reduce the need for additional maintenance over time.

Here’s the not-so-tiny point from this tiny house—all these products that help make this tiny house energy efficient and durable can and do play the same role in that 2,700 square foot house. Insulation, sealants, doors and windows, siding—plastics can help these products save energy for pretty much any homeowner. That’s not a tiny contribution to sustainability—that can be huge.

Maybe the tiny house movement eventually will lead to a reduction is the average size of houses. Maybe not. But if the movement can raise awareness of steps that all homeowners can take to save energy, then that’s a movement everybody can get behind.