All-Electric Net Zero Energy Homes in a Cold Climate

All-Electric Net Zero Energy
     Homes in a Cold Climate:
                  Can it be done?

Presented by:                              For:
        Eric Doub, President and Founder                GreenBuild 2008
              Ecofutures Building Inc.              “Extreme Green” Session
                Boulder, Colorado                 Thursday November 20, 2008
          www.ecofuturesbuilding.com                     www.usgbc.org

The Answer is “YES”

It doesn’t have to be this extreme

                    You can always turn
                    off your main
                    breaker to be truly
                    zero energy!

Or this either…

This kind of extreme is certainly beautiful, fun, and probably very
liberating, but it’s not for everyone.
Many homeowners want their hot tubs, margaritas, and 3000+
square feet and to still be green.

Another version of “extreme green”

Homes that are:
„   Beautiful
„   Comfortable
„   Easily understood
„   “Fully Loaded”
And still:
„   Net-zero energy
„   Net carbon neutral

Solar Harvest Net-Zero Energy Example

Net-zero energy is not about
doing without or being miserly

Making NZEH less extreme requires:

„   Using commonly available materials
„   Relying on known technologies
„   Prescribing methods easily understood by the trades
„   Producing easily replicable designs
„   Depending on and trusting your HERS rater, third party
    verification team or quality controls specialist

Not-so-extreme NZEH Building Basics

          A quick review of
    “Build tight, Ventilate right
   and Reduce indoor emissions”

Assemblies: much more than R-value
Net-zero energy homes need enclosures with:

„   Insulation
„   Thermal breaks
„   A complete air barrier
„   Good design that minimizes the risk of
    moisture damage according to building
    science best practices

A few examples (methods we have tried)
                   “THE BASIC”

               „ Complete air barrier
          „   Thermally broken in 1 place
               „ Adequate insulation

The Solar Harvest option
                     “THE PREMIUM”

                        2x6 STUD

                 „ Complete air barrier
            „ Thermally broken in 2 places

                „ Even more insulation

     „   Double drywall for distributed thermal mass

A high altitude challenger
                       “THE CADILLAC”
                       aka. “THE SLAM DUNK”

                  „Completely thermally broken
        „ Adjustable insulation depth with bigger air gap

          „ Double drywall for distributed thermal mass

„   More complex exterior trim is possible, with no foam sheathing

Windows: looking past the frame and the glass

                           „   Double pane is good
                           „   Triple pane and Heat
                               Mirror films are great
                           „   Gas is a plus
                           „   Thermally broken
                               frames are a must

   BUT… when thinking about windows, it’s not just
          about the glass and the frame!

Windows: looking past the frame and the glass
                          „   With 20% glazing or more…
                              ‰   Harder to get to net-zero energy
                              ‰   Much harder to get to HERS 0
                          „   And if 20%+ glazing is desired,
                              movable insulation is even more
                              important

                              “No matter what you do to beef up
                              your envelope, if you’ve got too many
                              windows, getting that HERS score
                              down to 0 is just about impossible.”
                              - Aspen, Colorado HERS Rater

      Less overglazing, more thoughtful glazing!

Passive Gain, Actively Distributed:
Sunspaces reduce glare, sundrenching, and overheating while preserving
views and daylight

Onsite Renewables: a necessity

New developments in single family onsite renewables:
„   “Seasonal storage of thermal heat” being phased
    out in favor of “cloudy cold-snap storage” as our
    goal
„   “Grid storage” of Btus on the rise

NZEH & HERS

From a carbon neutrality standpoint, HERS and
  third party verification services are the key to
  making mainstream NZEHs work

               Government building inspectors alone cannot
               make up for the poor practices and behavior in
               the building industry

SAMPLE HERS RATINGS
                  Indian Hills, CO
            Conditioned SF: 4,700 ft2
      HERS Score From Modeling: 14
     Projected HERS Performance: 0
 Onsite Renewables: 10 kW PV + 180
                    evacuated tubes

                                        Evergreen, CO
                                        Conditioned SF: 3,500 ft2
                                        HERS Score From Modeling: 0
                                        Projected HERS Performance: 0
                                        Onsite Renewables: 10 kW PV + 240
                                        evacuated tubes

Boulder County’s BuildSmart

„   Where net-zero
    energy homes are
    not only more
    mainstream..

„  Net-zero energy is
   law!
(for homes 5,001 sf+)

Boulder County’s BuildSmart (cont.)

Boulder County’s BuildSmart (cont.)

Boulder County’s BuildSmart (cont.)

            (and Remodels)

        As the amount of new or
      remodeled area goes up, the
     HERS requirement goes down

(amount of new and remodeled area is based
  on the ratio of new/remodeled to existing)

Boulder County’s BuildSmart (cont.)

Now that we know it can be done…
and codes like BuildSmart require it to be done…
We need a package of tools and methods that will make NZEH:

Mainstreamable
                                     &       Scalable
What does this package look like?

                  Commonly available materials
                    Off-the-shelf technologies
  Easily repeatable methods that are understood by the trades
       Codes & standards based on energy consumption
 Reliance on HERS raters and third-party quality control teams

NZEH & Cost
„   Stick-built: Main cost drivers are
    ‰   Size
    ‰   Shape & corners
    ‰   Finishes
    ‰   Architectural details
    ‰   But NOT onsite renewables (7 – 10%)

                          VS.

Solar Village Homes

                                                     12 models so far!

„   Manufactured by All-American Homes
„   Near-Net-Zero right “out of the box”
„   Cost: $150 psf sitework thru turnkey move-in ready
    ‰   Including PV, Solar Thermal, and all interior finishes!

Coppersmith Way Development

Photo and sidebar from Solar Today Nov/Dec 2008
(www.solartoday.org)

NREL’s Habitat for Humanity

The 2030 Challenge:

   The fossil fuel reduction standards:
Today          2010         2015          2020         2025           2030

              60%             70%          80%          90%       Carbon-neutral!!!

                          Is this so extreme?
                          …NOT FOR LONG!!!!!

“My professional goal is to become average, for our work to become unremarkable.”
                                                                             - Eric Doub