How BIM Helps Deliver High Performance Housing with Greater Quality + Profitability
THE DEEPER STORY
Virginia builder/developer Jay Epstein was an early adopter of green, high-performance building techniques. He was involved in the Building America program from its inception in the 1990’s and more recently won three Housing Innovation Awards from the Department of Energy—in 2016, 2017 and 2018.
Now he is using DIGIBILT for the design and management of the state’s First Net Zero Ready community, the 75-home Walnut Farm in Williamsburg.
Jay hopes the project will serve as an example of what BIM can do for production builders in general and green production builders in particular. “I want this community to demonstrate what’s possible,” he says.
Streamlining the Design + Bid Processes
He likes that the model offers a 3D rendering of the home’s structural and mechanical systems both in isolation and in relation to one another, which helps him solve conflicts at the design stage rather than suffering from field variances. The fact that the underlying data will display price and schedule implications that result from any changes and options, as well as generate a complete bill of materials (BOM), has proven to be a real time saver.
Eliminating Waste + Reducing Production Costs
For simple unit-price estimates like roofing or insulation, the very accurate BOM has led to significant cost savings. In the past, subs submitted turnkey bids that included material costs, but the model makes it a simple matter to separate those costs and eliminate waste. He can send the framer a list of the exact number of studs and sheathing panels the home needs and get a more accurate labor bid based on those numbers.
The BIM also helps shave cost from more complex jobs like HVAC. “We can create very efficient duct and plumbing layouts,” Jay says. “This saves the mechanical contractor design time and reduces variances. Once they understand that, we see the savings reflected in the bid.”
While some subs were skeptical at first, they embraced the new system after a trial run. This is a tactic many builders have used successfully when transitioning to BIM. “On the community’s first home, I told everyone that we would monitor the work to make sure our estimates were accurate,” he says. “Then I reminded them that there would be another 74 homes to do.” All his subs have gotten on board and some trade costs have fallen by 30%.
In fact, Jay confirms DIGIBILT’s estimate of net savings—after all the provider’s fees—of $14,000 on a $440,000 home. All that savings goes to the bottom line.
“The building industry is the second least digitized in the world. It’s time we grew up and started building smart.”
Enabling High Performance
The above benefits are ones all builders should be interested in, but how does BIM help with the design and construction of green, high-performance homes in particular?
Epstein’s homes are all Zero Energy Ready: they have HERS scores below the mid-50’s and can supply all of their annual power with a modest solar array. The path to designing and building such a home starts with good design then moves through a series of decisions about construction detailing, equipment choice, plug loads and renewables, with each decision set building on the ones before it.
The BIM model makes the decision-making process easier. It shows how every system in the home fits into the overall design and lets the builder quickly see how different choices at each of those levels will affect the budget. Data from an energy modeling program like REM/Rate can even be imported into the model.
Jay believes that benefits like these will become more important as homes become more complex. For instance, he is building to what he believes will be code in 2025. His homes include structural details like insulated ZIP sheathing and conditioned crawl spaces, as well as mechanical equipment like 20 SEER variable speed heat pumps that coordinate electronically with the home’s ERV. He says the BIM technology helps him manage the design and installation of those systems.
The model also helps him demonstrate benefits to customers that have always been hard to communicate. “We can show them what’s behind the walls and explain why those details will make a difference in their lives,” he says.
For instance, the homes at Walnut Farm will have looped structural plumbing layouts and on-demand recirculating pumps. By getting hot water to fixtures more quickly, the plumbing layout will save each homeowner an average of 7,500 gallons of water annually. Using the model to show this and other systems helps customers see what they’re getting from him that they wouldn’t from another builder.
Quality Assurance
In addition to BIM, Epstein is also using some of DIGIBILT’s other features. This includes “BILTiD”—basically, a unique code for each house that’s analogous to a car’s VIN number. The model and all related information is stored permanently in the cloud (via Amazon Web Services), and authorized users can go online anytime in the future to call up that information. They can see everything that went into the house and how it all fits together.
They can also see the completed construction schedule, the results of blower door, duct leakage, and other tests and certifications the builder might have had done, such as the HERS rating, the LEED score and ENERGY STAR compliance.
The system even helps him with quality control. For instance, he is using flash-and-batt insulation with open cell foam sprayed on the inside of the frame as an air seal. Jay built the critical path schedule to ensure that the siding goes on after the foam and that the job supervisor takes photos of the inside of the frame after the siding is complete. If the photos show siding nails penetrating the foam, then it’s not thick enough and will have to be re-sprayed.
These pictures, as well as photos of other critical details like window flashing, three-stud-corner insulation and duct mastic, become a permanent part of the home’s BILTiD record. Epstein says that his subs appreciate this. “It’s a quality monitoring system they don’t have to pay for.”
Attracting Next Gen Talent
One final benefit has to do with the future. At 68, Jay is looking to transition his company to the next generation. He believes that the use of sophisticated digital technologies like BIM, along with the natural appeal of green building, puts him in a strong position to attract young talent.
The bottom line is that while most industries have embraced digital technology and run with it, a lot of builders are still moving at a crawl. However, Epstein believes that Zero Energy Ready homes and communities are the future and that anyone who wants to create will need a high-tech business of the future. “The building industry is the second least digitized in the world,” he points out. “It’s time we grew up and started building smart.”
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