Beyond Basic Training

Learning to build a Habitat for Humanity home exceeds mere how-to sessions.

Content courtesy of the U.S. Department of Energy. Edited by Green Builder staff.

Class is in session every day on a Habitat for Humanity job site, so it is no surprise that Habitat for Humanity North Central Connecticut (HFHNCC)’s “Cleveland Avenue Home” won the “Class is in Session” Grand Award in the 2023 U.S. Department of Energy (DOE)’s Zero Energy Ready Home (ZERH) Housing Innovation Awards (HIA).

Habitat for Humanity North Central Connecticut built a 3-bedroom, 1.5-bath, 1,396-square foot home—the “Cleveland Avenue Home”—with the help of dozens of volunteers who utilized DOE Zero Energy Ready Home program performance criteria.

The organization gets about 5,000 volunteers a year—from corporate, faith, and civic groups to high schools and colleges—making them the largest group HFHNCC educates on an annual basis.

“Every shift starts with an explanation and demonstration of what, how, and why we do things a certain way,” said Director of Construction Kristopher McKelvie. “There are a lot of conversations about the importance of DOE ZERH construction and why it benefits our homeowners. Given the extent and diversity of our volunteers, our reach and impact with this group alone is significant in the community.”

HFHNCC takes homeowner education seriously as well. “Many of our Habitat homeowners are first-time home buyers and they have a lot to learn, so we start the process early to educate them about their home,” McKelvie explains. “Prospective Habitat homeowners must complete 150 hours of ‘sweat equity.’ They help build walls, install radon pipes, connect duct work for the ERV unit, and so much more. The hands-on experience helps them understand the function of each component.” 

Once the home is completed, HFHNCC provides a thorough in-person walk-through. Homeowners are shown where filters are located, how they are cleaned or replaced, how to monitor and maintain each system, and the importance of simple behaviors such as keeping windows and doors closed to allow the ERV to control the interior air quality.

“I developed an educational training video based on the DOE Zero Energy Ready homeowners’ manual,” McKelvie says. “The video reviews all the information from their in-person walk-through, and critical information about owning a DOE ZERH.”

Homeowners have access to this and other online training and can contact Habitat directly with any questions or concerns as they ease into their new home, McKelvie adds.

Promoting ZERH Benefits

Before families move in, HFHNCC hosts a home dedication event, which creates another opportunity for the affiliate to educate the greater community on sustainable homebuilding methods.

“Everyone involved in the construction of the home, neighbors, sponsors, and anyone from the general public can meet the family, tour the home, and learn more about what DOE Zero Energy Ready construction involves,” McKelvie says.

“These events always garner media attention, which often leads to further inquiries from home builders and curious individuals into how we achieve DOE ZERH standards and what that entails.”

Participation in the DOE HIAs has also helped the affiliate increase awareness about sustainable construction and the DOE ZERH Program. The Habitat affiliate won its first DOE Housing Innovation Grand Award in 2020 after building its first certified DOE ZERH.

The success of that build motivated the affiliate to commit to building all of its new homes to the DOE ZERH standard. HFHNCC has certified 10 homes and won three HIAs plus two Grand Awards.

“The media attention we garnered after completing our first ZERH generated great interest locally and nationally,” McKelvie says. “We received requests for personalized tours, copies of our house plans, and cost breakdowns from other affiliates, home builders, architects, and schools.”

HFHNCC spoke frequently with local news outlets, presented at conferences, and provided case study data to help other builders construct to DOE Zero Energy Ready standards.” These interactions provided us with a great opportunity to discuss the benefits of DOE certifications for the builder and homeowner, McKelvie says.

The affiliate now has four different house plans that have been modified to meet DOE ZERH certification. As it expands into different neighborhoods, HFHNCC will continue to improve upon and modify its designs. “We are committed to showing that DOE ZERH construction is valuable and needed,” McKelvie notes.

“DOE ZERH significantly reduce utility costs and provide healthier indoor air and comfortable climate control for families,” McKelvie explains. “As a builder, there are incentives and rebates to help offset expenses.” The affiliate estimates it costs about $10,000 more to meet the DOE ZERH criteria than just building to code. Current energy incentives in Connecticut cover the additional expenses.

Excited About Construction Requirements

Every home certified through the DOE Zero Energy Ready program must meet the criteria of ENERGY STAR Certified Homes Version 3.1 or 3.2 and the U.S. Environmental Protection Agency (EPA)’s Indoor airPLUS program.

Builders must also meet other efficiency requirements such as:

• Hot water distribution requirements of the EPA’s WaterSense program.
• Insulation requirements of the 2015 International Energy Conservation Code.
• HVAC and water heating efficiencies.
• Third-party verified air sealing targets.
• Installation of ENERGY STAR appliances, windows, and lighting.
• Ducts in conditioned space.

In addition, homes are required to have photovoltaic (PV) panels installed or have the conduit and electrical panel space in place for future installation.

The use of insulated concrete forms (ICFs) provided a solid air seal in the walls from the footings to the underside of the roof.

The DOE program offers considerable leeway in what building assembly methods the builder can choose to meet the insulation requirements. HFHNCC typically builds stick-frame construction, but for this project it used ICFs for the exterior walls.

The National Concrete Ready Mixed Association and the CT Concrete Promotion Council donated concrete, forms and training. McKelvie was happy with the ICF construction, but noted it took longer due to coordination with contractors, suppliers and city inspectors.

Construction Project Manager Diana Gasca says the volunteers were excited to try the ICF blocks, which consist of two rigid foam panels 8 feet long, 18 inches tall, and 2.625 inches thick, held apart by plastic spacers to form hollow blocks 11 inches wide.

The blocks are stacked like bricks, and steel rebar is laid across the spacers horizontally and vertically. Then, the hollow wall is filled with concrete that hardens in place to form a very sturdy mold-, pest-, fire-, and wind-resistant wall. 

“It’s like adult Legos,” Gasca says. “I would give a quick demo in the morning. Then we would jump into it. The volunteers did everything.” 

Volunteers put the walls together, cutting them to size where needed, reinforcing the forms, and created an alignment system for pouring the concrete. They sealed the seams with canned foam where needed but they didn’t need to seal most of them because the ICF product forms very tight seams, according to Gasca. 

A subcontractor installed a spray-on polymer-modified asphalt liquid-applied membrane and an insulated protective drainage panel over the exterior surface of the below-grade ICF foundation walls. The exposed area between the ground and the vinyl siding was covered with a parge coating that resembles concrete. The vinyl siding was attached directly to ICFs at integrated vertical 1.5-inch fastening strips located every 8 inches across the ICF wall.

The vented attic was air sealed around light boxes and drywall seams before 17 inches (R-60) of cellulose was blown in over the attic floor. Raised-heel trusses allow 14 inches of insulation over the top plates. A strip of sill gasket was stapled into the corner formed by the top plates and ceiling trusses to air seal the corners before installing ceiling and wall drywall.

Volunteers installed the windows under the supervision of Gasca or one of the three experienced volunteer crew leads on site. The windows were installed in 2-by-12 window bucks and set flush with the exterior walls then sealed with flashing tape and a high-performance polyurethane sealant around and over the nailing flange.

At the encouragement of its energy rater, the affiliate chose triple-pane windows. The vinyl-framed windows were made in Maine and had an insulation value of U-0.22. “Going from double pane to triple pane, we got a better HERS Index score, and it made it quieter inside the home,” says McKelvie.

The ICFs provided a solid air barrier and contributed to the overall air tightness of the home, which had only 1.48 air changes per hour at 50 Pascals pressure differential of air leakage, he adds. 

To provide fresh air to Cleveland Avenue Home, an energy recovery ventilator (ERV) was installed with volunteer labor. The ERV draws in fresh outside air that is warmed by heat transferred from outgoing air. The incoming air passes through a MERV 8 or 13 filter before being distributed throughout the home.

A ductless mini-split heat pump provides very efficient heating and cooling to the home at a heating efficiency of 14.0 HSPF and a cooling efficiency of 33 SEER.

The heat pump has one outdoor compressor and two indoor air handlers, one for each floor of the home. In-wall transfer fans located over bedroom doors pull heated and cooled air into the bedrooms at the flip of a switch when doors are closed.

Looking to the Future

Building energy-efficient and durable homes has always been a priority for the HFHNCC. After considering several certification programs, the affiliate adopted DOE’s Zero Energy Ready program as its new standard because DOE did the initial hard work of analyzing and recommending best practices to achieve an airtight and high-performance home, according to McKelvie.

“What we discovered was that making simple changes to our designs, and thoughtful use of materials and equipment, would allow us to achieve the DOE Zero Energy Ready certifications without having to drastically modify our building style, house plans, or budgets,” he explained.

Homeowners have been extremely appreciative, McKelvie notes. “It’s more comfortable living,” he says. “It’s less drafty and it’s easier to maintain a consistent temperature in the house. Because we’ve switched to heat pumps, the homes now have air conditioning in the summer. Also, many families with kids have seen greatly reduced allergy and asthma symptoms.”

The affiliate is in the process of constructing a cluster of 10 DOE Zero Energy certified homes on a single land parcel in East Hartford. It broke ground in June 2023; plans call for having all homes completed by the end of 2025.