The increased desire for homes that are healthy, sustainable and efficient, or green, is catalyzing some long-overdue innovation in the homebuilding industry. With this innovation, however, comes a degree of risk, both for homeowners who are selecting features that are the best expenditure for their budget, as well as for the builders who are trying new methods that may leave them legally responsible for failing systems.
After working on high-performance products and passive-standard projects for over 10 years on three continents, I wanted to share a few ideas about where I think we should be focusing our attention, and what high-level lessons we can learn. Homeowners and homebuilders who know what to watch for can take advantage of the newest sustainable building technologies without leaving themselves liable to potential failures of new methods.
Mariana Pickering (Emu Building Science)The article author’s first Passive House project, in Cavriago, Italy
1. Building to Code Does Not Eliminate Risk of Moisture Damage or Poor Indoor Air Quality
It’s important for builders and homeowners to understand that localized building codes are developed painstakingly over time with a great degree of compartmentalization and politicization.
For example, the most recent versions of energy-efficiency codes have started to require air sealing as a strategy for conserving energy losses. This is a fantastic development in the movement toward consuming less energy, but it has unfortunately left many homes subject to moisture damages due to a lack of understanding about vapor movement and ventilation.
Alpen High Performance ProductsBreezeway Passive House project featuring Alpen Passive House windows
In other words, even though local building codes are improving incrementally over time, you shouldn’t assume that building to code will provide you with a healthy or comfortable home, much less a green one.
Product PicturesA tradesman applies sealing tape to a window install to ensure resiliency against moisture.
Air sealing is good. Buildings should not breathe through their walls. The mechanical ventilation system is in charge of this, much like we breathe through our respiratory system, not our skin.
Fewer air leaks means better building durability, higher energy efficiency and lower energy bills. With airtightness, however, we need to have a better understanding of moisture control and ventilation to avoid condensation, mold, poor indoor air quality and, eventually, health concerns.
Household air pollution was rated the third most significant cause of ill health for the world’s population, according to the World Health Organization. Exposure to poor indoor air quality can cause headaches, dry throat, eye irritation, a runny nose, asthma attacks, infection with Legionella bacteria, carbon monoxide poisoning, cancer, respiratory and cardiovascular diseases, myocardial ischemia, angina, high blood pressure and heart disease. It can also cause a financial burden stemming from decreased productivity due to poor sleep.
That’s why air sealing without a moisture-management strategy can be dangerous.
Mariana Pickering (Emu Building Science)What can you do as a homeowner? Consider a third-party building code, like Passive House, that sets performance criteria above and beyond what your local code requires, based on international best practices.
Ask a lot of questions of your professional team involved in your home project. Try to obtain the results of your home’s Blower Door Test, shown here, which should be required in areas meeting the 2015 International Energy Conservation Code.
A lower number means it’s more airtight. Code usually requires 3 or 4 ACH50 or less (ACH is air changes per hour during the test, at a pressure of 50 Pascal). Passive homes require 0.6 or less, a drastic difference.
Generally speaking, a builder that can build more airtight is often more meticulous with other details as well and will have a higher quality of construction. If your builder doesn’t inspire confidence on these subjects (or even if they do), consider hiring a third-party representative, such as a building science consultant, to advocate for you and help the builder meet the project goals.
Zehnder America, IncAlso, find out if the house will have a continuous (that part is important) ventilation system, either a heat recovery ventilation (HRV) system or an enthalpic recovery ventilation (ERV) system with at least an 80 percent efficiency rate.
An HRV is a simple box involving fans, filters and a heat-recovery core where outgoing air passes incoming air without mixing. In very dry or very humid climates, the best scenario is an ERV, which also balances moisture.
Mariana Pickering (Emu Building Science)What can you do as a homebuilder? Learn, learn, learn. Continued education in building science can help you get a grip on heat and moisture flows through assemblies.
Consider courses like the Certified Passive House Tradesperson workshop, which my colleagues, pictured here, and I put on a few times a year near Denver, and where you can learn about air sealing, moisture management and indoor air quality. The North American curriculum is also licensed to other qualified trainers across the U.S., and builders can express interest in finding a course near them by joining a waitlist for their city.
If you want to combine your continued education with an international trip, check out the international events calendar for training opportunities.
ZNC – Zola’s No Compromise Passive House WindowZola Passive House windows in the Sunshine Passive House project
2: The Biggest Bang for Your Buck Is in High-Performance Windows
Statistically speaking, if you’re in the U.S., whatever you’re thinking of as a high-performance window is probably not. Historically, American manufacturers have been far behind Europe in the sophistication of available products.
That is starting to change, with some truly amazing products now made in the U.S., but you may need to search a little deeper and save in other areas of your build to offset the expense. Instead of spending your budget on systems that compensate for consumption, like larger photovoltaic systems or geothermal heat pumps, you could allocate those funds to better windows that also bring more comfort to your home.
Not only do high-performance windows guarantee comfort, they also contribute to a consistent indoor environment, which is easier to ventilate, purify and keep clean and healthy.
G. Christianson Construction, Inc.What can you do as a homeowner? Do your research and prepare yourself mentally. Yes, high-performance windows cost substantially more than code windows, and there’s just no way around that.
We need to shift our mentality to think about the entire building assembly as a highly engineered product itself. Investing in the thermal envelope will allow you to save money on heating and cooling equipment, energy bills and long-term health bills. Not to mention, high-performance buildings are quiet, less dusty and more comfortable.
Mariana Pickering (Emu Building Science)Building envelope expert Enrico Bonilauri teaches a class of builders about high-performance window installations using a mockup with Alpen windows and Thermalbuck.
What can you do as a homebuilder? Rely on your professional network. Hire experts early and often to model performance. The aerospace industry doesn’t build a plane, see how it flies and then build another. It builds virtual prototypes.
A builder who is not modeling the performance of a building prior to construction is at a competitive disadvantage and cannot fail fast enough to iterate to a better prototype.
Find yourself a building science consultant who will make their job to check your designed assemblies for heat and moisture flow so you can focus on the business of building.
Justin Pauly Architects3. Remember That Buildings Are for People
I always start projects by reminding my clients that buildings are for people. It seems an obvious statement, but somewhere in the discussions about how to meet code, how to meter energy usage and how to stay within budget, we tend to forget that small fact.
Americans spend 90 percent of their time in buildings, and at least a third of that is at home in bed. For me and many others who specialize in passive building, the green building movement is not about energy balance. It’s more about health and comfort.
NZ Builders LtdPassive design strategies like proper orientation, compactness of form, well-designed shading and high-performing windows can help you conserve before you compensate.
Using passive strategies throughout the design process helps streamline the pathway to reaching net-zero (when your home annually produces more than it consumes), because you have less consumption that you need to compensate for with renewables. And along the way, you’re paying attention to health and comfort instead of only the energy balance.
AwairAn indoor air quality monitor, like this Awair unit, measures data points like pollution and moisture, and it gives you a qualitative score that you can track via an app on your phone.
What can you do as a homeowner? Use your power as a consumer to push for transparency in the process. Get an indoor air-quality monitor, specifically one that measures Particulate Matter PM2.5, such as the Awair monitor and app, pictured here.
Splurge on an infrared camera (I like the Flir One, which fits on an iPhone) and look to see where thermal leaks are happening in your thermal envelope.
Being involved as an informed client means you have a better sense of the massive amount of information your builder is trying to juggle. Manage your expectations, and prioritize.
And remember, all of these principles can be applied to retrofits just as well as new construction. The best way to think about any home-improvement project is to have it be a steppingstone toward a larger goal. If you can afford to take only small steps, just make sure you are making those steps in the right direction so you don’t have to redo or undo work later.
For example, the most cost-effective point in time to make renovations is when you were going to anyway. Maybe a hailstorm ruined your siding? That may be a good time to go ahead and take a look at your insulation as well. Broken window? Why not go for a high-performance model? Even if it’s only one, you can replace them over time.
What can you do as a homebuilder? Communicate more and better. As you’ve probably figured out, home ownership is an emotional journey for many. Managing expectations can go a long way, and discussing potential areas of concern early on can avoid disputes later in the process.
High-performance building requires a more integrated approach to designing and building, and ideally also to the storytelling aspect of client management. Get them on board by learning with them as they ask questions.