High Performance Tiny House, an Experiment
In graduate school, I chose to focus on the work of Finnish architect, Alvar Aalto, during a study abroad trip. One of the buildings that stood out, was his Experimental House, on the island of Muuratsalo, Finland. In the early 1950s, Aalto bought the island and built this house for his own experimentation. As I stood in its courtyard, I thought to myself, “One day, I, too, will build an experimental house.” Like Aalto, I wanted to explore with materials, room sizes, scale, textures, homeowner experience, construction techniques, and so much more. Reading about and being told, by my professors, what works and why, doesn’t hold a candle to experimentation and experience.
Our very own experimental house
Apart from buying an island, and instead of it being just me (no one is an island), Jodi and I are doing what Aalto did over 60 years ago. We’ve designed and are now building our very own experimental house in the woods. Instead of Finland, though, we’re building ours along the banks of the Withlacoochee River, in Central Florida (Hernando County), where Jodi grew up. For the geeky folks reading this, that’s Climate Zone 2.
We’re calling our little cottage the High Performance Tiny House, and this is our experiment. No part of the process is off-limits from being experimented with, including us designing and building for ourselves. We’ve not done that before! Wish us luck!
Why is called the “High Performance” Tiny House?
“High performance” is a new-ish phrase in the design and building industries. High performance homes are designed and built to last a really long time, are reliably comfortable, don’t make the people in them sick, and need little to no energy to work. Oh, and they’re beautiful. They are as appealing and as functional as any other house in the world. Some of the main things that set them apart; durability, comfort, health and energy consumption.
To create to a high performance design, and before we design the mechanical systems and select product, we prioritize these five control layers in the building enclosure design.
Then, we get out there and build it, to make sure that the design is properly executed and that our control layers stay in tact!!
The last layer, aesthetics, is one that we don’t hear talked much in the building science community (a bit of a geeky crowd), but it’s necessary. Absolutely! If a house doesn’t look good, its owners are less likely to take care of it, and that’s just a shame. Not to mention, not durable.
The High Performance Bungalow (completed: 2015), in Roswell, GA, and the Proud Green Home at Serenbe, (completed: 2012) in Serenbe – Chattahoochee Hills, GA, are recently completed examples of high performance homes, that exemplify what comes from paying close attention during design and construction.
While we are the direct beneficiaries of this design and construction experiment, our current and future homeowner clients will get the added benefit of having many of these ideas, techniques, systems and products tested out, with our own hands, before we apply them during the construction of their own home. A true testimonial! We’ll come out of it knowing whether the stuff is practical, and whether it really works the way it’s intended. So far, the track record is good.
This will be an experiment in everything, from home space planning, to building science and installation best practices, finishing techniques, mechanical systems design and operation strategies, product selection and use, and a lot more. We will also do plenty of performance testing and monitoring along the way, and after its completed. Testing will keep us on target, and monitoring will tell us how things are performing after its finished, including how much energy we need to live in the high performance tiny house, and how much moisture is in the air and the walls, floor and roof. This is a critical part of every project. No reason to guess, or cross fingers. Proof is possible! Just ask Grace and Corbett Lunsford, of the Building Performance Workshop, the folks we’ve asked to do all diagnostics testing of the Tiny House.
P.S. Check out the Tiny Lab on Wheels, that Grace and Corbett are building right now, and the crazy cool Proof is Possible Tour they’re taking it on. If they get to your city, be sure to go say Hi and learn about their Tiny House!
By the way, the target infiltration rate (i.e. the amount of air leaking through the cracks, gaps or holes in the building enclosure) of the High Performance Tiny House is less than 0.2 ach50, or 0.001 ELR (Envleope Leakage Ratio). We’ve done it before. We will do it again!
To make sure that what we learn through our experiment is shared with the world, beyond this blog and our social media channels, we’re inviting industry leaders to join us, and work with us on some of their own experimenting. We’re offering it up as a “test house”, for the research & development and marketing teams from the various manufactures, and local tradespeople, that we feel meet or exceed our high expectations for performance, durability and design.
Products, like plumbing and electrical fixtures, exterior cladding, drywall and other finishes, will be put to the test, as well. Some of them new products, others have been on the market for awhile. Other R&D teams, and tradespeople, will join soon, and we do have a few other slots to fill, so if you are interested in being a part of the experiment, we’d be glad to hear from you! What we choose will need to meet or exceed our criteria for durability, performance, and timeless design trends.
So far, we have a good roster:
- Huber Engineered Woods – We will be using their wall and roof OSB sheathing, ZIP System, with integrated water and air control layers, sub-floor sheathing, flashing tapes and liquid flashing. Among other things, we will work together to measure the home’s air leakage through an infiltration and exfiltration (blower door) test before the windows are installed, after windows are installed, after all penetrations are sealed, and when the house is complete.
- AVI Marvin – Using the Integrity by Marvin windows, and with AVI’s help, we will be looking at thermal performance, air tightness, and ease of installation. Because they are a supplier, and not the manufacturer, we will also have a focus on service. This can go a long way to making a process successful, and AVI has stepped it up, several times, to save the day.
- Mitsubishi Electric Cooling and Heating – In addition to how to heat and cool tiny houses, especially those with very low loads, like ours, we will be looking at ways to manage internal moisture loads in low-load homes, and how to apply what we learn on a tiny scale to the larger scale. We will be looking at a situation where the moisture removal capacity of the smallest cooling systems will be as much as five times the actual moisture (absolute humidity), and we will be experimenting with ways to remove the moisture without supplemental de-humidification. Using a whole-house monitoring system, from PowerWise, we will keep an eye on relative and absolute humidity, indoor and outdoor temperature, as well as COP (coefficient of performance) and other performance metrics of the variable refrigerant flow, mini-split heat pump system, with ductless wall mounted air handler.
- Panasonic Ventilation Systems – As mentioned above, we will have a lot of opportunity to experiment with how to deal with interior moisture loads, but will also need to deal with the moisture loads from the fresh air ventilation. With our air leakage target as low as it is, we don’t anticipate much contribution to latent loads from outside air leakage. Using a combination of the spot ventilation fan (bath exhaust) and an in-line fan (by FanTech) bringing in a controlled amount of outside air, we will be looking closely at the effectiveness of this as a fresh-air ventilation system. The fresh air will be brought in, near the air handler to be picked up by the return, so it’s filtered, and conditioned before distribution.
- ROXUL Insulation – The perfect wall approach is catching on in the industry, and insulation is a critical part of making it work. Exterior, continuous insulation is a good idea in any climate where condensation can occur with enough of a temperature difference between inside and outside the house. Yes, that means Florida, too. We are working with ROXUL to look at more than just the thermal performance of the floor, walls and roof assembly, in this climate zone. We’ve used a modeling program, called WUFI, to verify the thermal, water and vapor control (a.k.a. Hygrothermics – drying potential) of each assembly. The hygrothermic properties are one of the greatest assets of, and why use rigid stone wool on the exterior (ComfortBoard IS) and stone wool batts in the cavities, (ComfortBatt). Another really awesome property of rocks is that they don’t burn!! BONUS!! We will have a “perfect” assembly, that will be uninterrupted around the entire assembly.
We’ve broken ground!!
This past week we broke ground on the High Performance Tiny House, and we’re excited to share progress and photos, with you all, on our Facebook page, as well as our other social media sites. Please follow along. We will be sharing every step of the way , along with our industry partners.
Instagram – @claumergiddens