Tuesday, January 31, 2017

Modular Home Factories React to Net Zero Challenge

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.


Harris - Finish Werks said...

Gary, I cannot express enough my excitement at the response rate you received, and the obvious interest in building far better than Code. Kudos to all these folks for reaching higher.

Three things I want to point out...

1. Standardized Definitions:
While the concept is relatively new, we need to make certain we're using the correct language of building energy efficiency. "Net Zero" has been largely determined by the performance nerds at Resnet, DOE, EPA, NGBS and other certification entities to be inferior to "Zero Energy Ready" and "Zero Energy". "Net Zero" was confusing to home buyers when polled in focus groups... "zero" what?? Zero water usage? What does "net" mean? Zero Energy is a much clearer description. ZER is the home without renewable energy.

2. Builders do ZE; manufacturers do ZER:
We must understand that modular manus do not build Zero Energy homes. They deliver a large part of the home, sometimes with HVAC included. But they can never be more than ZER. We builders are responsible for making delivered ZER modular homes Zero Energy. We are responsible, as GC, for air sealing the modules, duct blasting, blower door testing, specifying Tier III Energy Star appliances, fitting out LED lamps, and everything else that is finally scored by a HERS Rater. And of course, we must install the solar PV array that makes a very tight ZER home (HERS Index = 40) a true ZE home (HERS Index = 0).

3. ZER does not mean PH:
While Beracah has had some success with Passive House (walked through one), I’ve said for years that this heavily (overly) insulated building method will always experience diminishing returns. Many building science nerds have found that you can only insulate so much before the thermal improvements stop paying for themselves. The money saved by stopping at a reasonable thermal enclosure can be spent on the solar PV – which even a PH must have in order to hit HERS 0. Unless and until supply chains deliver the particular PH components more cost effectively, PH will and should remain an outlier for only the well-heeled. ZER can be accomplished by any existing modular manu today, and you do NOT have to spend like Blu!

Anonymous said...

I don't see it this way guys. I agree somewhat with Mr. Mertz that "net zero" is a marketing term or slogan to most people. I do not think the real money cares as much for the planet as they do their comfort and security.

Who is the real money? The Boomers! They got the money in their iras, their 401ks and their lifetime of saving. Millenials have neither savings nor income to do this thing.

'Net zero', government rating systems, the $$ a builder shells out to assure a certain rating, these things obfuscate what I think the buyer wants . Comfort, value, and security in knowing the house is well built to suit their needs.

I am much more comfortable with building a good house than chasing slogans. The one I've got coming up in south central pa is a very good of what a baby boomer client wants. Performance is more important to someone with 25 years remaining to their lives then social conscience. As a custom build the use of a competent Rater and a $300.00 report AND a good blow door and infra red pic should add a lot more actual value then any public certification.

The kids are still mostly broke and when they buy, it's a production home. Let the volume production guys go on about net zero. Remember, we are coming into an era of less bull shit. Be hopeful!

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