Tiny House, Tiny Energy? Part 1

July 08, 2017
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Fall 2017
This online-only article is a supplement to the Fall 2017 print edition of Home Energy Magazine.
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This is part 1 of a two-part series on Tiny Houses.

For those who are seeking to reduce their carbon footprint by living in a super energy-efficient house, the choices have been limited to a small selection of “energy-efficient” production homes, or multifamily buildings where the energy “loads” are distributed over a greater floor area, making the units themselves proportionally more energy efficient than a stand-alone single- family home of the same size.

Each state has energy efficiency requirements for newly constructed housing. Most follow the International Residential Code (IRC), which is the model building code of the International Code Council (ICC). This code defines building construction requirements, including those related to energy efficiency. Not all states use the most current version of the IRC, and many are painfully slow to adopt the code’s current, more aggressive, energy efficiency requirements. Because of this, production builders must track each state’s energy efficiency requirements as they build. Depending upon market competition, they must also decide how they want to attract buyers. Most production builders simply build to the minimum building code the local jurisdiction uses. Builders may choose to stand out from the pack and offer some “energy-efficient” homes based on some recognized criteria, such as Energy Star or LEED, in an attempt to attract eco-minded buyers. Typically, these “energy- efficient” homes are only a small portion of a builder’s inventory, so the buyer has to keep a sharp eye out to find one of them.

A Third Option

What if there were a third option? The American Dream of homeownership is not the same as it once was, for various reasons. Previous generations of homeowners expected to work hard and make house payments for 30. Today, some folks believe their quality of life depends less on material goods and more on freedom from anxiety, financial pressures, and social “norms” that inhibit happiness. Some are choosing an even more simple lifestyle and smaller, more practical spaces to live in. Some are choosing to go Tiny.

A Tiny House is a self-contained living unit of up to 400 square feet. These microabodes are often built on trailers for mobility. Others are built conventionally and put on foundations. The Tiny House movement has been quietly growing and is starting to show up on the radars of news agencies, TV shows, local governments, home buyers, home builders, empty-nesters, first-time buyers, career changers, and the like. Tiny Houses are an option for those less inclined to chase the old American Dream—who instead are carving out their own slice of happiness.

In essence, the Tiny House folks want a simpler lifestyle. They do not want to be tied down to a job or a location that they feel has sucked the life out of their lives. If you talk to a group of Tiny House enthusiasts, you’ll soon discover a common thread. That common thread is freedom, independence. Freedom could mean freedom from a mortgage, freedom from a job you have to drive to every day, freedom from a geographical location because you don’t like to be tied down to one spot, or freedom to do what you want when you want because you’ve whittled your expenses down so low as to make that possible.

As a high-performance building evangelist, I am always on the lookout for new concepts, designs, and ideas that will get us closer to a net zero structure that is no more expensive than one that is not net zero. Is Tiny House a potential answer? Well, it depends on whom you ask.

Most families (Mom, Dad, two-plus kids) probably won’t survive the confines of a Tiny House. Living in a Tiny House is not for the faint of heart. For Tiny House on wheels (THOW) designs, the floor area rarely exceeds 300 square feet, mostly due to highway restrictions and towing requirements. Tiny Houses built on foundations (THOFs) can be more creative with layout and design, since there is no load to balance as there is with a THOW. In either case, the livable real estate in a Tiny House is a lot smaller than most people are used to. Most of us are used to small, confined spaces only when we’re out camping in some small cabin or RV or taking a trip on a sailboat. We seldom spend each day under these cramped conditions. If you have children, you may find it challenging to cohabit in a Tiny House. There’s no sending a child to his or her room—there’s only one room! A typical THOW has a main area serving as the living room, dining room, entertainment area, and work space. There is usually a small kitchen, one small bathroom, and a sleeping loft.

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Tiny House living space utilizes every inch for practical and efficient design. (Photo courtesy of tinyhousebuild.com)

Multifamily building advocates can boast that their inherent designs makes these buidings more energy efficient. They typically have less exterior surface area (representing potential heat loss) in relation to the amount of conditioned floor area. In addition, multifamily buildings often have centralized systems to provide domestic hot water for all of the units, which is typically more efficient than having an individual water heater for each unit. These larger, centralized systems may also be greener from a resource standpoint, because less equipment is being produced and used to deliver the same outcome. A potential downside to living in a multifamily building is that it means you may have neighbors above you, below you, and on either side. Some people enjoy having this sense of community. Then again, there’s something to be said for having your own ”cave,” whatever your ideal “cave” looks like.

Brian Rubin, an architect and Passive House (PH) designer, along with his wife, Siena, a carpenter and soon-to-be architect, loved the idea of a Tiny House so much that they set out to build one for themselves. They live in the San Francisco Bay Area, where homes are very expensive. When asked how they were preparing to live small, Brian said, “We’re used to small spaces. We lived together in a 250 ft2 apartment back in Brooklyn. It was one of our favorite places to live.” To them, the size of a home is less important than healthy, comfortable, sustainable construction. Their goal is to design and build a Tiny Home.

A Tiny House is small, but is it more energy efficient than a single-family home of comparable size? That’s a tricky question on many levels. To make a fair comparison, we should look at legal construction practices. Even with all its popularity, the current Tiny House movement is still somewhat on the fringe legally, and many Tiny House owners are struggling to find legal places to park, live, and prosper.

Those seeking to play by the rules and have their Tiny House be a legal structure currently have two options. One option is to buy or have built a THOW that is certified as an RV. This makes for safer construction, because meets RV standards, and it’s easier to get the THOW insured and licensed. The downside to the RV approach is that most jurisdictions do not allow full-time residency in an RV. If you’re planning on having your Tiny House be your primary residence, the RV approach may not be the wisest choice, depending upon where you want to live.

The other option is to build a foundation-mounted Tiny House, or THOF, that meets the local code requirements. The ICC has just adopted the Tiny House Appendix (originally known as RB 168-16) for inclusion in the 2018 IRC. A THOF built to the requirements of the Tiny House Appendix is more likely to receive a certificate of occupancy. However, this depends on whether the municipality in question chooses to adopt the new appendix. Some will, some may not, especially because, as an appendix, it is not considered part of the main body of the code.

This newly recognized Tiny House Appendix adds a much-needed safety component that was virtually nonexistent in previous Tiny House builds. A lot of Tiny Houses are "homemade," with no oversight whatsoever. This new appendix offers Tiny House builders the necessary exceptions to code requirements concerning ceiling heights, stair dimensions, and so on that can drastically affect Tiny House design and usage.

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The Morrison’s Tiny House is built on a trailer so it can be moved anywhere on their property and beyond. (Photo courtesy of tinyhousebuild.com )

Before this appendix existed, one could still theoretically build an IRC code-compliant home with a floor area of around 100 square feet, including a bathroom. Fortunately, or unfortunately (depending upon which camp you’re from), most local governments and municipalities have made 1,000 square feet the minimum floor area for a single-family house, and most aren’t eager to lower that number. When pressed to explain, most agencies will say it’s a “revenue thing.” “That’s an easy problem to overcome” according to Andrew Morrison of TinyHouseBuild.com. Morrison, the lead author of the new IRC Tiny House Appendix, suggests that “jurisdictions could simply require a permit fee ‘minimum’ regardless of square footage and throw out the 1,000 square foot rule.” The other objection municipalities may raise as a hurdle to accepting Tiny Houses in their communities is neighborhood acceptance. Most Tiny House rule challenges involve complaints by neighbors or others who don’t understand and appreciate the objectives of the movement.

Currently, there are no code jurisdictions for permanent housing that are interested in dealing with THOWs. This includes HUD, the American National Standards Institute (ANSI), the RV Building Code, and the ICC. Building codes are designed for homes that are stationary, not movable, and this makes writing codes for THOWs rather difficult. Some Tiny House manufacturers seeking legitimacy have gone the route of treating their Tiny Houses as glorified RVs and have certified them under the ANSI and RV codes. The problem with this approach is that it is illegal in most jurisdictions to live full time in an RV. I, for one, would rather not have to move my home every 30 days to stay out of trouble with the law.

If we look at a home built on a foundation, we can assume that it will be built according to the local code requirements as they relate to insulation, fenestration, and the efficiency of equipment and lighting, among other things. Thus a home built in Alaska will not have the same characteristics as a home built in Florida, and this is a good thing. But a THOW cannot alter its characteristics every time it crosses a state line. So how does one write one building code for THOWs that could be applicable in all circumstances? This is a challenge that the building industry has to meet.

learn more

Brian Rubin: Projects supporting sustainable, smart design.

Tiny House Build: Featuring tiny house construction workshops and clinics and introducing the new Tiny House Code: Appendix V of the 2018 International Residential Code (IRC)

Create Your Freedom: Learn how to achieve a simpler life (website to be released soon).

Joe Giampietro, AIA, CPHC (email): Bringing Tiny House + Passive House construction practices to community colleges.

Learn more about the following products:
Lunos E2 HRV low-energy ventilation system.
Roxul natural insulation products.
475 High-Performance Building Supply.

Is Smaller More Efficient?

Can we assume that all Tiny Houses are inherently more energy efficient than conventionally built homes? At first glance, we assume that we can increase energy efficiency just by reducing the volume and floor area of the living space. HVAC systems are designed for the climate, occupancy, and volume of the space being conditioned. By simply reducing the volume of the space that needs to be conditioned, we can lower the necessary capacity of the equipment being installed. When I asked Graham Irwin, AIA, a Passive House trainer, designer, and consultant, whether Tiny Houses are actually more energy efficient, he said that “although Tiny Houses may have a smaller utility bill, they actually could be less efficient, simply due to the exterior envelope to interior floor area ratio.” Houses that are being designed to meet the PH standard are modeled using the PHPP (the Passive House Planning Package). This is a robust energy-modeling tool that takes into account all energy features, including building assemblies, geographical location, and even the number of proposed occupants, to predict a home’s energy performance. “I like Tiny Houses,” Irwin says, “ but I have some reservations about the performance of them, due to their size. There’s a lot of surface area in relation to the [conditioned] volume. It’s easier to have a large home seem more efficient when analyzed through the PHPP, because the floor area to exterior envelope area ratio is beneficial. In larger homes, for the given amount of square footage, you have less exterior envelope, and when you make the building tiny it’s the reverse.”

Kevin Beck is a senior energy analyst for the Association of Energy Affordability.

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