Dörken Systems & Fine Homebuilding: Achieving the Net-zero Ideal
Today, net-zero energy initiatives are taking the building industry by storm. These are homes designed and built to generate as much energy as they consume, once all renewable energy systems are fully installed—with the goal of reducing the energy needed to maintain them. According to a standard set by the NZEC, net-zero energy structures are those that supply a minimum of 90% of their own annual energy requirements. In addition to achieving optimal energy efficiency, net-zero-energy homes are also considered healthier and more comfortable because of passive design strategies like natural ventilation and daylighting. As a result, they require lower operational and maintenance costs and help reduce emissions, all while providing occupants with optimum living conditions.
Although this ideal is achievable, the pursuit of net-zero-energy construction can be quite challenging, especially without the right planning in place. For building professionals who are searching for solutions, incorporating effective products that help enhance building envelope performance is key. Of course, one of the most important elements to consider as part of a net-zero approach is the role of the air and moisture barriers.
How do air and moisture barriers help with energy efficiency?
Fundamentally, the role of air and moisture barriers is to keep wind, water, and weather out of the system. However, there are two key factors that make a barrier stand out when it comes to achieving the best in energy efficiency: the membrane’s vapor permeability and its air tightness. First, vapor permeable air and moisture barriers allow any moisture within the structure to escape via diffusion and, second, a high-performance air and moisture barrier resists air movement, and therefore moisture, through increased air tightness.
A Case in Point: In California, All New Residential Construction is Set to be Net-Zero Energy by 2020
To help provide some context, Dörken is currently involved in a net-zero-energy residential project by Designer and Contractor Atmosphere Design Build. The project, named Good Haus, is the family home of designer Mela Breen and builder David Good, and is currently under construction on a steep and rocky hillside that spills down onto a small neighboring foothill meadow in Nevada City area. Covering this significant net-zero construction is Fine Homebuilding—the most widely read home construction magazine in the U.S. By highlighting key details of this home’s construction, Fine Homebuilding aims to offer designers and builders the critical information they need to build to the advanced standard of the Good Haus.
Protecting the Foundation and Keeping the Basement Dry—DELTA®-MS
The construction began with building a unique foundation that comprises two parts: a traditionally poured basement to house mechanicals, and an elevated slab placed on top of a pan deck to support the remainder of the house. The reason the traditional basement for mechanicals was integrated is so that it can easily be insulated and air sealed to help create a clean, dry space within the conditioned envelope. This best-practice approach in the industry was chosen because it helps reduce standby energy losses and improve the air quality flowing through the ventilation duct.
“In addition, the basement was stacked beneath the kitchen and bathroom to reduce long mechanical runs, which curbs standby losses and eases the complexity of the construction,” narrates a Fine Homebuilding representative in this video. “While the elevated slab is quite a common detail in commercial construction, it proved to be beneficial in this construction because it allows the home to sit lightly on the land, helping give it the distinct and modern look.”
The product choice for protecting the basement from water and moisture was DELTA®-MS, a dimpled membrane that uses Dörken’s exclusive Air-gap Technology to ensure that basements stay dry and last longer. DELTA®-MS allows water to drain and effectively bridges cracks so that no water intrusions can occur—this wall waterproofing ensures healthier and more comfortable living spaces for home occupants.
Advanced Roof Protection Using a High-performing Weather-resistive Barrier—DELTA®-VENT S
The unvented roof assembly relied on exterior sheathing as the primary air barrier, creating uninterrupted transition of the air barrier from the walls to the roof. The roof was sheathed with plywood and taped to serve as the primary air barrier at the top of the home, then covered with the weather-resistive DELTA®-VENT S prior to the insulation. DELTA®-VENT S is a heavy-duty, highly permeable air- and water-resistive barrier that increases airtightness—meeting the project’s net-zero-energy goals. In addition, all of the plywood seams were taped with DELTA®-MULTI-BAND as a “belt-and-suspenders” approach to ensure an airtight assembly.
Exterior Air Barrier for Optimal and Comfortable Interiors: DELTA®-VENT SA
DELTA®-VENT SA was chosen for its industry-leading properties, as a critical component in achieving energy efficiency throughout the build. The product is also highly vapor permeable, allowing moisture to escape and eliminating the risk of mold and other problems caused by water pooling. In addition, DELTA®-VENT SA improves the performance of the wall system by adhering directly to the substrate, meaning that fasteners are not required.
Throughout the DELTA®-VENT SA installation, the product’s self-adhesive feature came in quite handy as it stuck to the plywood sheathing in one step to create an effective air seal. Moreover, one of the key considerations for choosing the product is that it was chosen as part of a family of products—meaning that the builder and installer did not have to worry about compatibility issues between flashing tapes and WRBs. DELTA®-MULTI-BAND was first used to wrap the edges of the overhang to ensure a good seal, followed by DELTA®-VENT SA to achieve an airtight seal.
The Right Installation Technique for Windows for Optimal Performance and Durability
Another important feature of airtight homes is the windows and doors, so proper installation techniques were critical. With a faulty installation, a lot can go wrong around penetrations like windows and doors—if gaps are left open, for instance, air is allowed to move through the system, which can be troublesome for the performance of the house and the comfort of its occupants.
For this reason, the team used DELTA®-FLASHING, which was taped on the still and corners to ensure the integrity of the air and water barrier. DELTA®-FLASHING is a high performance durable, self-adhering flashing that really worked to help the enclosure system achieve both air tightness and water tightness.
The construction of the Good Haus has come a long way, but there’s still plenty to do to get it to the next phase to completion. For insight into the next phase of the construction, follow the coverage on Fine Homebuilding.
In net-zero construction, every input and process, no matter how small, needs to be considered as part of the overall contribution to the energy efficiency of the home. By working with experts and using the best in design, product selection, and building processes, Good Haus is on the right path to achieving the net-zero ideal. Fine Homebuilding’s California 2018 Good Haus is a perfect example of an energy-smart, connected, healthy, and durable building that will offer comfortable and energy-efficient interiors to its occupants.
For more insight on Dörken’s involvement in Fine Homebuilding’s California 2018 initiative, click here.
Watch Dr. John Straube dive into the importance of airtightness and how it’s critical for maintaining a building’s performance.