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The views expressed in these articles are solely those of the author and do not reflect the views of EEBA staff, officers, or board members. EEBA welcomes guest articles from qualified authors, and we offer these articles as a service to the high-performance housing industry as a way to encourage discussion and collaboration between industry professionals on relevant issues.

Posts From November, 2019

High Performance Basic Training

Some of the things I learned at Houses That Work
High Performance Basic Training

Although the 2021 version of the International Energy Conservation Code has yet to be finalized, chances are it will get most new homes very close to Net Zero Ready. Builders and architects need to understand the best ways to meet the code requirements for a particular floor plan in a specific climate without creating moisture, health, or other problems.

The escalating demand for building science knowledge on the part of industry professionals is why, over the past few months, we have encouraged people to attend EEBA's annual Summit, a 3-day educational and networking event with the top designers and builders of green, high-performance homes. This year's gathering was October 1-3, and in our last article EEBA President Geoff Ferrell offered an insightful summary of how Summit attendees are shaping our industry's future.

But of course, the once-a-year Summit isn't the only education that EEBA offers.

There's plenty of gold in our full-day training seminars: Houses That Work, High Performance Mechanicals, HERS Associate, Selling High Performance Homes, and Path to Zero. These are scheduled all year throughout the U.S. (as well as at the Summit) and offer great value not just for industry newcomers but for those of us who think we've nailed the basics.

I place myself in that latter group. After writing about building science on and off for nearly three decades, I decided to attend Houses That Work, which I assumed would be a helpful review. It was all that and more. Eight hours with instructor Andy Oding was truly humbling, because it drove home how much I did not already know.

EEBA's trainings are designed to complement each other. For instance, Path to Zero (which I wrote about a few months ago) focuses on "how" to design and build Zero Energy Homes, with instructor Bruce Sullivan giving students a menu of options they can choose from. Houses That Work covers more of the "why." It's the basic building science everyone needs to make informed decisions about those options.

The seminar's underlying principle is that high performance building requires a systems approach in which walls, roofs, windows, insulation, air sealing, and HVAC are all recognized and treated as interdependent systems. It presents the foundational knowledge of that approach.

Code mandates are making a grasp of those interdependencies more important than ever. "It's just a matter of time before every new home in North America will have to meet Net Zero standards," said Oding. However, the airtightness and insulation levels needed to get there create risks that require skill and knowledge to mitigate. "If you want a more efficient, more durable, healthier home rather than one with condensation in the walls and sick occupants, then you need to understand the principles behind how all the home's elements interact with one another," he adds.

A grasp of these principles will provide insight on how to design and build great homes using today's materials in ways that avoid problems while delivering the benefits homeowners want. That's the definition of a house that works.

The basic information presented in the course offers value to pros of all skill levels. Topics covered include: how air, heat, and moisture move through a structure and how changes in various parts of the system affect those flows; insulation and air sealing strategies; the importance of windows, roof details, and mechanical systems; principles and strategies for keeping rainwater and groundwater out of the structure (no small matter considering that 80% of building failures are water related).

The course also includes illustrations of these principles in action, as well as other details that builders and designers can use in their work. There are too many to go into here, but I'll mention a few:

Loads are changing. "Thirty years ago, the largest energy load and the highest energy cost by far in most homes was heating," says Oding. Today, air conditioning is a bigger expense than heating even in northern climates. "That's because a lot of heating is done with gas while all cooling is done with more expensive electricity."

This makes SHGC for windows more important than ever, even in Northern climates.

Windows have taken center stage. Back in the 90's windows accounted for 8-10 percent of the average home's wall area. They were important but not a super big deal. Today, however, 18-25 percent is more typical, so windows have a bigger effect on bottom-line performance.

Oding worked on a research study for a major window manufacturer and found that in cold-climate homes with those window ratios, upgrading from double to triple pane glass (with U-values of .25 to .20) can add more R-value to the home than putting an extra two inches of foam on the exterior—a result that will be confirmed by a Manual J or HERS Software tool.

Warmer glass has another benefit—reduced condensation potential in the winter. "At those U-values it could be -10 outside, but with a healthy indoor relative humidity of 35%, you might not be able to see any condensation on the interior glass."

What does this mean? "When people see ice dams they often immediately think they need more insulation," says Oding. "But if you understand how insulation affects stack effect you realize that you really need to pay more attention to air sealing."

Continuous exterior insulation will be the rule up north. Exterior insulation is a good idea in cold climates but Oding believes it will become a code requirement for Zones 5 and higher sometime in the next 10 years. He says it's a durability issue. Exterior insulation helps the building last longer by controlling the dew point (e.g. limiting the condensation potential at the back side of the exterior structural sheathing).

Behavior matters. Once you have succeeded in creating a new, Zero Energy Ready Home, according to Oding, the biggest loads tend to be occupant loads: cooking, bathing, clothes washing, and lighting. These occupant loads can make up 50% to 60% of the total energy use in such a home.

Builders can help the owners of these homes save more energy by helping them choose more efficient appliances and educating them on the consequences of their behaviors.

Clean air is HUGE. The US EPA estimates that Americans spend about 90 percent of their time indoors1, so it's no surprise that air purifiers are a multi-billion dollar business and one of the world's fastest growing industries.2 Nonetheless, a recent survey for VELUX suggests that people perceive that we only spend about 18 percent of our time indoors, highlighting the general confusion that persists—and the consumer education that is still needed—surrounding indoor air quality (IAQ).

Oding insists that some consumer air purification devices have limited impact and that good IAQ requires eliminating the sources of the problem (like wet materials, chemicals) and providing the home with well-designed mechanical ventilation (an HRV or ERV). "IAQ is an emotional issue that’s very important to most people's decision making," says Oding.

This is obviously a great opportunity for high-performance builders who offer real indoor air quality improvements.

Visuals have power. If you've gone to the trouble of building a Zero Energy Home, then you need to show people the benefits.  

Oding cited a UK study in which people who saw an image of thermal bridging in their homes were 4.9 times more likely to do something about it. With infrared cameras available that fit on a phone costing as little as $250, there's no reason a high performance builder can't show the difference between their homes and typical, code-minimum construction.

In fact, Oding says that when he worked for a Canadian production builder, it wasn't unheard of for a client to use an infrared camera to confirm that the home was properly insulated and air sealed.

Of course, if you take a Houses That Work seminar, that scrutiny won't be a problem. That's because you will be on the way to designing and building homes of such high quality that you welcome it.