Last week a Challenge was made to our industry by Ken Semler, President of Express Modular, about what builders and factories were doing to achieve Net Zero in the homes they are building and selling.
With that in mind I sent out an email to a dozen East Coast modular home factories asking them what they are doing to meet the Challenge. Not everyone replied which is not unusual anytime a group of people are asked to reply. In fact, the national average for people replying is less than than 5%. My question had a 25% reply which is absolutely remarkable. Way to go Modular Home Factories!
It was interesting to learn that factories are all embracing some aspects of Net Zero in their current building methods. Some are reaching Net Zero, others are striving for near Net Zero and all of them are using High Performance construction techniques in their factories.
Here are the responses I received:
Jason Webster, Huntington Homes:
Huntington Homes, Inc welcomes the code goal of Net Zero homes. Because clients are already demanding it. We have found the goal of Net Zero very easy to achieve. In 2016 just over 20% of the homes we built were Net Zero ready. That is, they had no fossil fuel fired mechanical systems and a building envelope robust enough to be heated and cooled using only electrically driven heat pumps (geothermal or air source). Add solar panels and these homes are true Net Zero.
I don’t think that Net Zero as a goal is that difficult to achieve. By definition Net Zero means that on an annual basis a building is producing (using renewable energy) as much energy as it’s consuming. Technically you could make any structure Net Zero by changing the mechanical systems to electric and adding enough renewable energy to it.
What gets confusing is when people (builders, clients, energy advocates, etc) mix The Goal with A Strategy.
On a spectrum of Strategy I see the following.
On one end is the Low Load Home (think Passive House). Very high levels of insulation. Very even temperatures inside (both over time and location). Very expensive to build. Add little amounts of renewable energy to make the home Net Zero.
On the other end is a standard code built home with all electric mechanical systems and a whole bunch of PV generating a whole bunch of electricity to make things work. This is probably the cheapest way to go Net Zero. But it’s also the most uncomfortable to the occupant. Temperatures inside the home vary uncomfortably both over time and location.
I think the balance point is somewhere in the middle. It’s easy to find the tradeoff point where more PV is less expensive than more insulation. But comfort can only be found with experience.
I think it’s in the builder’s interest to find this balance point before the regulators do. Because my experience with the Regulators is that they’re too influenced by the Low Load Strategy folks. Whereas the Goal might be less expensive to achieve some other way.
Dave Mertz, Simplex Homes:
Simplex Homes has had inquires for “Net Zero” homes but have found after continued discussions, what the customer really wanted was a high performance home and the term “Net Zero” was more of marketing term and they were not seeking a home with zero energy consumption.
We have not pursued the ‘Net Zero” concept but we have embraced many building techniques that would help us prepare for Net Zero. We offer and use the following: spray foam, with the flash and batt insulation, cellulose blown in insulation in the side walls to achieve a grade one installation, caulking to the top and bottom plates, air sealing all electric, HVAC and plumbing penetration, minimum expansion foam, high performance windows with an R-9 value, solar preparation, etc.
Additionally our plants are SBRA approved, (System Built Research Alliance) which is recognized by Energy Star as an approved method for in plant inspection to offer an Energy Star ready home. Additionally we have a Certified Field Inspector working here.
Dan Hobbs, Virginia Homes:
At Virginia Homes, when we talk about Net Zero – energy production equal to or greater than energy consumption – the first objective must be to minimize energy consumption. In so doing, the requirement for energy production is minimized. My comments are focused upon the consumption side because building the home so greatly influences that side of the equation.
Below is a pie chart of energy consumption in a home. Clearly this varies from region to region, but this is the overall situation for the US.
Taking the largest consumption first, Space Heating, we focus upon energy efficiency including:
Envelope sealing
Insulation/thermal breaks/efficient window packages
HVAC optimization (in conjunction with the builder)
In regards to lighting, the second highest consumption, we are moving rapidly to
LED lighting wherever possible.
Recently we examined new LED lighting which is both efficient and low priced. I anticipate we will phase out of all incandescent/fluorescent lighting within several months. For water heating, most of our clients remain with electric tank water heating although we are moving to tankless systems in a number of higher end homes.
Further enhancing the energy efficiency of our homes continues to be a major initiative of Virginia Homes.
Mark Leishear, Beracah Homes:
Beracah Homes in Delaware is a leader in Net Zero and passive house manufacturing. Here is an example of expertise.
Vermont energy partners approached the Delaware sustainable energy utility and Milford housing with an idea to create an affordable/net zero housing unit that was modern, one unit, something people could put on their property if they were contemplating a manufactured house, as some people have land that they just end up putting one of those.
This is designed to target a certain audience that will be able to build a better house instead and still keep a similar footprint. As the design made it self to be something they could build in the factory, they contacted us about building.
Since we had built two passive houses already, we were happy to partner with them on this project. We are putting the model out at our factory so people can tour. They are also going to put another model out at their location as well. There are some interesting specifics regarding financing and I am not too familiar with all those, so I cannot speak regarding.
Most of these projects that we build come to us from architects or groups.
Homeowners have not come yet specifically requesting to build net zero.
I now want to Challenge modular home builders to share their experience in working with their customers in producing Net Zero, Passive House and High Performance homes.
Since it seems to be the consensus of the factories that this will be customer driven, what are you, the builder, doing to explain this to your home buyers.
