A Systems Engineering Approach

By: Kevin Brozyna

The Best Practices Research Alliance Lab Home, built by current Builders Association of Central Pennsylvania (BACP) member and Alliance member S&A Homes, finished construction late last fall.  The Lab Home is part of a multi-year research initiative focused on developing cost-effective design practices that will enable production homebuilders to deliver affordable, net zero energy homes throughout the U.S.

S&A partnered with IBACOS®, the founder of the Alliance and a team leader for the Department of Energy’s Building America program, because the Alliance goal of making net-zero homes feasible on the production level fit well with S&A’s focus on offering high-performance and high-efficiency homes to all their customers.

Using materials and construction practices that are currently commercially available to builders, IBACOS and S&A Homes designed and constructed the 2,700 square foot home to use about 81% less energy than a comparably sized home constructed to current code standards.  They accomplished this through the use of a super-insulated and air-sealed building enclosure, triple-glazed windows, a highly efficient ground source heat pump, energy saving lighting and control systems, Energy Star appliances and an on-site renewable energy system consisting of a 3.8 kW solar PV array. But the house would never have achieved these numbers if not for a 15-month design process founded on the principles of a systems engineering approach.

A systems engineering approach enables a builder to more effectively design a home that can achieve higher levels of quality and energy savings. The first part is Teams and Whole-House Assessment, which brings together the key stakeholders, such as the builder, trades, material suppliers, and possibly code officials, most of whom work independently in a typical production building environment. Through a collaborative work effort, they assess the building as a whole, recognizing that the design of one component can greatly affect the performance of other systems in the house.

Another critical aspect of systems engineering is Design and Construction Evaluation, where the stakeholders work together through the design and construction process to identify the best strategies and system interactions between the site, enclosure, mechanical systems, and energy use that will result in efficiencies of time, materials and energy.

“In a typical design and specification process, the trades, material suppliers, and the builder’s organization will work in isolation from each other,” said Kevin Brozyna, the Lab Home Project Manager. “You often find that even communication between different departments within a builder’s organization is non-existent.  Most of the time each stakeholder is only thinking about the part of the home they are responsible for rather than how they can improve the overall efficiency of the home.”     

An integrated design approach is collaborative and iterative, and should be a fundamental part of the process to ensure design efficiencies are recognized for homes at any level of performance. But execution in a high-performance home design process, like the Lab Home, is even more critical, and where a small change in a system’s performance can result in big consequences.

During the Lab Home’s design process, “we held several pre-bid meetings where we invited groups of contractors, including the HVAC, framing, plumbing, insulation, and electrical contractors, to our office to sit down together and discuss the project goals and proposed designs,” said Brozyna.

These meetings gave the trade contractors and other stakeholders the opportunity to identify areas of concern in the design and suggest alternative approaches that would be favorable for each of the parties. This meant the trades knew what the builder was expecting of them, what they could expect from the other trade contractors and what challenges they would face before they arrived on-site. Materials and systems were also selected and agreed upon beforehand, so that each part would work efficiently together.

For example, the design team designed the open web floor trusses to provide the right amount of room in the floor system for the HVAC ductwork and plumbing services to be installed, without needing to add bulkheads or soffits.

Brozyna added that the Alliance team continued to work with the trades throughout the construction phase to iron out problems and ensure collaboration with all the parties rather than competition.

“A systems engineering approach shouldn’t be just for high-efficiency homes,” said Brozyna. “These principles and practices can provide benefits for builders at any level of home performance.”

Kevin Brozyna works with trade contractors during Lab Home construction