excerpt: designing a der
TRANSCRIPT
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THE GREENED HOUSE EFFEJEFF WILSON
R E N O V A T I N G Y O U R H O M E
A D E E P E N E R G Y R E T R O F I
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A Hole in the Bucket: Sealing the Envelope
The building envelope is just what it sounds like: everything that
goes into keeping the outdoors outand the indoors in. Starting from
the exterior surface of a house, a building envelope consists of siding
and roofing, housewrap or roof underlayment, a sheathing material
(usually plywood or oriented strand board, which is not particle-
board, but an engineered wood panel made by layering strands orflakes of wood in specific directions, which are then bonded with
resins under heat and pressure), the structural members (studs and
rafters, for example), insulation material, and even interior finish
surfaces (such as drywall and paint). Fixing the building envelope
is the most critical part of a DER because it affects everything inside
the envelopeheating and cooling efficiency, humidity levels, in-door air quality, and comfort all depend on a well-designed building
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FIGURE 3.10Often, older homes are not insulated. When insulation is added later to walls and ceilings, th
and basement arent usually included and air sealing is rarely addressed. The ideal deep energy retrofit bri
building envelope, thermal envelope, and air seal layers into alignment to act as one continuous protective
Insulation layer
Air sealing layerAttic
Living space
Basement
Attic
Living space
Basement
Attic
Living space
Basement
AN OLDER,
UNINSULATED HOME
THE LIVING AREA
INSULATED
A PROPERLY
RETROFITTED HOME
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can develop if the retrofitting of these spaces is done incorrectly. I
explain this in more detail in chapters 5, 6, and 7.
For now lets just say that air sealing and insulation, which
improve your building and thermal envelope, are the first things
youll want to concentrate on in your DER design. Like I said
before, insulation is like a sweater that your home wears and air
sealing is the windbreaker. And just as a windbreaker alone wontkeep you comfortable in frigid temperatures without an insulating
layer, a sweater alone wont keep you comfortable in a biting wind.
You need both, and these layers are the foundations upon which
your DER rests. Depending on where you live, different levels of
insulation may be recommended, but homes in all heating and
cooling climates can benefit from air sealing. As a matter of fact, ifyour house has oodles of insulation but no air seal, your insulation
is not living up to its potential, so getting a handle on air sealing
h i i l
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DESIGNING A DEEP ENERGY RETROFIT
PLUMBING STACK VENT
BATHROOM FAN VENT
ELECTRICAL
OUTLET
DRYER VENT
ATTIC
HATCH
RECESSED LIGHTS
RECESSEDLIGHTS
CHASE
KITCHEN
FAN VENT
CRAWL SPACE OUTDOOR
FAUCET
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Exterior strategies typically require little interior demolition,
so occupants can remain in the home during the retrofit process.
The typical approach includes expanding the exterior wall or roof
surface outward with spray foam or rigid foam insulating panels.
While spray foam naturally air seals as it expands and cures during
application, rigid panel materials require careful manual sealing at
the joints with tape, caulk, or foam. Its also possible to perform an
exterior gut retrofit by removing all siding and sheathing before
filling the cavities with spray foam from the exterior. Once the
insulation and air sealing is complete, new exterior finish materials
are installed.
Many people overlook basements and crawl spaces in energy
efficiency improvements, but studies show that bringing the foun-dation into the thermal envelope can potentially save 30 percent
on heating costs. Exterior approaches, which require removing
l d i d i f di f d h f d
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new windows and doors installed by properly trained profession-
als. This is especially true in retrofitting applications: air sealing,insulation, and water management techniques that may be straight-
forward when installing windows in new homes can become tricky
when incorporating new windows into an older home. The energy
efficiency and operation of many high-end windows have been
compromised by a second-rate installation. This makes it doubly
important to hire a well-trained, competent installer.
The Working Parts: DER Systems
Once the building envelope strategy has been designed, from the
roof and walls to the basement or crawl space, then you can move
on to the systems. Your HVAC system is likely the biggest energyconsuming system in your home. If there were such people as av-
erage Americans, their biggest single point of energy use would
b h i hi h f l f ll
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an important aspect of a full DER. Following Energy Star recom-
mendations is a great start. Bright yellow Energy Star labels ensurethat youre buying an appliance that is at least 20 to 30 percent
more efficient than others in its class. But you can go further by
comparing those labels and choosing the most efficient appliances
within the Energy Star class. That label will also help you make
a better decision when an appliance fails and has to be replaced
quicklyEnergy Star has done most of the research for you and
made it easily accessible right at the point of purchase.
Automation and Monitoring
Last, consider energy monitoring and automation as part of a well-
rounded DER plan. Energy monitoring can show you where mostof the energy is being used in your home and, therefore, where your
money is going. Once aware of those facts, you might opt to change
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DESIGNING A DEEP ENERGY RETROFIT
can be automated to turn off when rooms are empty, appliances
automated to operate when electricity rates drop to off-peak pric-ing, and outlets automated to turn off when not in use, avoiding
the vampire loads of electronic devices in standby mode. Even
window shades can be automated to let sunlight in or shade it out,
depending on the season.
Does all of this sound a little bit Star Trek to you? Not these
days. We live in a land of touch screens and smart phonesits
about time our homes caught up. Using tablet technology, many
home automation systems provide easy user interface apps to
control any system in the home. These systems can cost from a few
hundred dollars for an off-the-shelf model to many thousands of
dollars for a custom system. Once these automation controls areinstalled, you can enjoy both energy monitoring and automation
for the most energy efficient operation of your home, so beam me
S ! hil l f h i i i l h d
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What Happened In Vegas
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Dream of Big Energy Savings
Thats the grand overview of a DER. Are you overwhelmed yet?
Dont worry, its natural to feel that way when considering a project
as involved as a full deep energy retrofit of your house. Take your
timedont rush the critical design stage and give yourself the lee-
way to dream big at the outset. Remember that a DER doesnt have
to be done all at once, but can be phased in over time, making the
individual phases more manageable.
By the time youre ready to start designing your deep energy
retrofit, youll have a professional energy audit in your hands, and
your auditors report will be a guide that youll refer to over and
over again during the design process. Depending on your comfortlevel you may want to hire an architect or you may feel confident
creating your design yourself. Either way, it helps to start by sketch-
i id h f i b ll
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homes systems will work better, replacing items as they fail. Our
DER took three years of physical work because we opted to do partsof the project ourselves.
While an entire deep energy retrofit is, by nature, not a do-it-
yourself project, you might have the skills to attack some parts of
your DER yourself. Sherri and I hired a contractor to handle the very
heavy lifting and steep roofing jobsthings that would have taken
me months to accomplish alone. Once the house and new addition
were under roof, she and I did the rest of the project ourselves, in-
cluding the exterior curtain wall retrofit and all of the exterior and
interior finish work. This took time but allowed us to minimize the
expense of our DER while still stimulating our economy by hiring a
local crew. Whether youre a hands-on or hands-off kind of person,researching and planning carefully will save you money and result
in a higher quality finished product.