ENERGY STAR for Homes Version 3: Assured Performance With Every Labeled Home




Uploaded by EPAENERGYSTAR on 17.10.2011

Transcript:
Welcome to a presentation on the new Version 3 specifications. For the first time since
ENERGY STAR was introduced in the market in 1995, EPA can now assure performance with
every labeled home. For the next hour, weíll cover how we can do that and how these new
specs bring complete building science to the housing industry for the first time.
Letís start with ìwhat is ENERGY STAR for Homes?î
Essentially ENERGY STAR does two things: we define what is truly energy efficient; and
then we provide recognition to our builder partners
for their commitment to the program. All of this is voluntary, and must work with the
housing industry in a way that meets their business objectives.
Growth has been exponential since we gained traction in 1999-2000. Weíve grown to over
1.2 million homes, and saw some decline in growth during the housing market recession
around 2007, but saw an increase again last year, even when the market continued to struggle.
You can see from the market penetration numbers that weíve achieved that energy efficient
builders are doing well in the market. There was a 40% increase in market penetration in from 2007-2008 alone.
Last year, almost 1 in 4 homes built earned the ENERGY STAR label.
Builder interest in the program has increased as well. 30 has grown to 300 builder applications
per month. So if ENERGY STAR is the solution, whatís
the problem and performance issues weíre trying to address?
It comes down to our core brand promise. We try to achieve truly energy efficient homes;
much better than code, we must be cost-effective, and we must treat homes that meet or exceed
consumer expectations. The performance we go after is the four cornerstones
that are made possible with building science. They are home with lower utility bills that
are more comfortable room-by-room, have healthier environments, and are much more durable.
We get there by controlling air-, thermal-, and moisture-flow. If we donít build as a
system and only implement energy efficient pieces, we canít control these things and
create failures for the home. Letís review how these occur, and start with
air leakage. With air leakage, you need to know the critical
applications. Two of these are the sill plate to the foundation, and sill plate to the flooring.
Hereís an IR image that shows just how much air leakage occurs without proper sealing at this application.
The light colors show warm surface temperatures and dark colors show cold surface temperatures.
So you can see just how much air leakage is coming through.
Doors, windows, and sill plates represent ~1/2 mile of cracks throughout the home. Each
window and door has a gap that must be fully sealed for them to work.
Another major gap just beginning to be recognized as an important building sealing detail is
the air gap between the sheet rock and the top plate, where there is an adjoining attic
above. Attics can get extreme temperatures, creating substantial driving forces at that
gap. Another source is through penetrations (often
leaky ducts) that go through the attic. The warm air melts the snow in winter. Once the
snowmelt reaches the eave, it cools and becomes ice. This can block drainage, and go up underneath
the roofing, causing damage to materials. Next item is insulation installation issues.
This is a significant problem because installers are paid by the piece; not how well the insulation
works. Key problems surfacing, mostly with batt products, are gaps voids and compression.
These can lead to convective losses that undermine the performance of the product.
A gap like the one shown through this IR image will be there for the life of most buildings.
People donít tend to rip off sheet rock and fix air sealing issues with existing homes.
Hereís a typical type of compression detail You can see the compromise in performance
from this image, which will last forever in the home.
Another way we see misalignment is through building practices like inset stapling of
batt insulation. The installer here staples the tabs of the insulation to the inside face
of the stud, often to expose the stud for gluing and nailing of sheetrock. But sheetrock
can be installed without gluing. Weíre accepting systemic misalignment for certain installations.
Hereís why the misalignment is so important: if I were to highlight the air spaces on both
sides of insulation that has been inset stapled, there are enormous gaps. Imagine if the walls
are extremely cold on a winter day. The only thermal resistance between the inside and
outside air is the sheathing and siding, which doesnít provide much thermal resistance.
Itís very likely that that air space on the outside wall would be freezing. Because of
the thermal transfer, the inside spaces, set at 70 degrees, are more likely to be in the
mid-60ís. The convective flow between the two air spaces can bypass the intended purpose of the insulation
altogether. This image shows how it can manifest itself
on a winter day. The insulating is hardly working better than the wood studs between
them. The walls should be the same color as the roof shown at the bottom of the image, but there is hardly
any control of thermal flow due to the systemic misalignment of inset stapling.
The outside sheathing on a winter day is extremely cold, and the air space between the framing
of the two floors is heated to room temperature. With the gaps, voids and compressions in this
insulation, thereís very little chance that there isnít condensation on this outside
wall as the warm air meets a cold surface. The potential exists for mold and moisture
if the wetting exceeds the builder materialsí ability to dry. Itís a risk we donít need
in construction. Again this IR image is strong evidence of
a significant problem. The band joist is exploding heat because the insulation isnít working
properly in that building application. Another significant detail that occurs is
misalignment at the ceiling. Here is an image of insulation draped across a false sloped
ceiling, leaving misalignment gaps. The ceiling goes into extremely hot temperatures
during summer. Another case of systemic misalignment is strapping
insulation below the ceiling framing. This is a consistent air space between the insulation
and sheetrock below. We see a very cold ceiling in the winter from
an IR camera. There are also critical gaps in attic hatches
and dropdown stairs. There are also significant problems in cases
where insulation is on a flat conditioned to unconditioned floor intersection, such
as a bonus room or cantilever. In summer the heat can flow around the insulation, creating
a hot floor for the bedroom above. In the winter, the warmer air in the room
flows out to the unconditioned space. Thereís no chance that this insulation detail
would be touching the floor above, creating a thermal enclosure.
And when this happens you wind up with a cold floor in winter, and hot in summer.
To show the importance of the whole system, hereís a house with walls and windows that
perform well, but the slab edge at the bottom is a superhighway of heat transfer. This will
effectively suck heat from the bodies standing on the floor inside.
Air barrier problems are also significant. In this case, fibrous insulation does not
equal an air barrier. It will stop thermal flow, but not airflow. So we need a 6-sided
air barrier in contact with the insulation for the thermal insulation to work properly.
The fibrous insulation here is dark and discolored. The driving force is driving air through this
insulation, making it a filter for dirt and dust.
Here is an infrared image of an attic kneewall in summer with inadequate air barrier.
This is a kneewall in the winter. The r-19 insulated space between the studs is performing
far below its rated r-value. Hereís a picture of a bedroom, where on the
backside of the wall is a sloped ceiling going down to a garage via unconditioned space.
You can see from the center image that this wall is very hot, likely above 90 degrees.
When the home was retrofitted properly with a 6-sided air barrier, however, the IR image
shows much improvement in insulation performance. Another key detail for stopping air flow is
where insulation runs up into the eave. Hereís an attic eave surface from the interior
on a cold winter day. In summer itís like a strip heater on the
edges of the building. Hereís another detail where the drop ceiling
occurs, and the insulation runs across without a lid.
The reason this is so important is that this leads to a thermal bypass without the air
barrier. This is the same thing shown via IR image.
You essentially have a complete thermal connection between the attic and the house.
Hereís a drop ceiling getting extremely hot. Thermal bridging occurs when lack of insulation
or poorly installed insulation allow for thermal flow thatís unintended.
This is much more wood than weíd need to hold up a house.
This creates a very big thermal bridge, where heat is transferring through the studs much
more quickly than it would with properly installed insulation with air barrier.
Another issue occurs at corners and wall intersections. The intersection of studs creates an air space,
which leads to cracking at corners. Hereís an IR image of wall intersection where
studs create uninsuilated space. Lastly, with thermal enclosure, windows need
to be addressed. Older windows that are not high-performance
let much more heat transfer occur. HVAC Quality installation is another part
of making a high-performance home. Often the builder and contractor are working together
to achieve the smallest cost, rather than greatest performance.
Essentially you pay for a 13 SEER, but get the performance of an 8 or 9 SEER because
of how the system actually performs once installed. Here are some examples of other issues that
have to do with quality installation. Leaky ducts mean that the air being conditioned
isnít getting to its intended location. Also ducts that are laid out without proper
design and installation create significant problems. Flex duct, for example, comes in
25ft rolls. By cutting the duct to fit a direct route, we cut back significantly on air flow
resistance. Every bend creates the equivalent of ~6-8 feet of extra duct length. There is
likely very little airflow coming out of B. We also need to watch compression of ducts
so they maintain enough volume to sustain airflow.
This duct is pinched like a garden hose, but instead of stopping water flow, itís stopping
the flow of conditioned air. There are also ventilation problems.
We need to make sure that moisture and pollutants can escape the home. Condensation is a good
indication of poor ventilation. But this can exist even where condensation does not.
There are also pressure balancing problems, if homes arenít properly equipped with systems
and fans to balance air pressure. This dark link in the carpet is an indication
of pressure balancing problems, as the air is trying to escape one room through the most
direct route. This is a diagram of why this happens. The
air handling unit pushes air into the bedroom, which then canít find its way back to the
central return. Once the bedrooms are pressurized to capacity, you stop getting the heating/cooling/dehumidification
that the system is supposed to provide, which can lead to setting T-stats higher in the
winter, lower in the summer, and compromising some roomsí comfort.
You can see from the change in readings on the right that when a bedroom door is closed
and the room goes into negative pressure, air gets pulled into the attic through the
light fixtures, and in just 20 minutes, the ceiling temperature changes 2 degrees.
Another example is the gap between the sheetrock and top plate.
This issue also affects how we place appliances. Clothes dryers are usually 250cfm airflow
to remove moisture in clothes. This creates a very big air exchange and creates a negative
pressure in the zone. The top of the water heater has a big hole
at the exhaust. These exhaust fumes are easily pulled back into the house.
A good indication of a problem exists at the bottom of this water tank where flame roll-out
appears to be occurring. Hereís a wall of a family room with laundry
room on the other side. With the dryer vent going through the wall up to the hot attic,
thereís always a hot surface condition. After running the dryer for 40 minutes, the
wall reaches as high as 90 degrees, which will compromise comfort.
Lastly, there are filtration problems when it comes to HVAC systems.
Filters often have large air gaps around the sides and tops, compromising performance.
They leave lots of particulates in the air. Then, there is the water management system,
which is important to be comprehensive as well.
Think of blow-drying your hair after a shower. It might take just a few minutes. With a piece
of insulation between the dryer and your hair, though, it will take hours, at best, to dry.
This is what has happened with high performance homes. Theyíre so well sealed and insulated,
that they have no tolerance for drying. If they get wet, you have almost certain moisture
problems. It becomes incumbent on Version 3 to include water management items to avoid
these issues in the first place. We need to look at draining moisture from
the home as a system, including roofs, walls, materials, and foundation.
Here is a house without any drainage plane on the walls. If moisture gets behind the
siding, there is a serious condition for getting the OSB sheathing wet.
Also every window leaks, eventually. Without pan flashing, there is much greater potential
for damage. Here is one case where there was enough moisture
that the material couldnít dry, and it led to mold and dry-rot issues.
Also the slits in foundation drains intended to remove water from the foundation can let
sediment in. These drains can clog easily over 7-8 years. Since most homes last 100
years, it would make sense to install drain tiles that donít clog in the first place.
Another critical area is where the roof intersects with an exterior wall. Without proper flashing,
IR images show just how wet it gets at this juncture.
We should also be protecting materials onsite so they donít get wet in the first place.
Those are the performance problems we believe need to be addressed for assured performance
in every home. And thatís what we attempted to address with
ENERGY STAR Version 3. Parts will not get this done. None of this
gets you a complete system. For ENERGY STAR Version 3, we ensure everything
needed for complete systems is included in the specifications.
We started with the underpinnings of controlling air flow, thermal flow, and moisture flow,
and included efficient equipment and 3rd party verification items to ensure high-performance
and complete the building science picture. All of these boxes come with every single
labeled home. The way this works is by starting with a baseline
specification which ensures the home is at least 15% more efficient than code, using
similar requirements as with Version 2. There are still prescriptive and performance paths
for getting to this level of performance. After this, there are mandatory checklists.
The two for HVAC are for the contractor and for the HERS rater.
The systems ensured by the mandatory checklists offer complete building science for every
labeled home. Weíll now go through the basic requirements of each of these checklist categories.
The first component targeted by the thermal enclosure system is air leakage. Version 3
targets the most critical applications first, requiring flashing and sealing, as well as
insulation. Typical details like these require a visual
inspection, as well as a blower door test to ensure the house is tight.
This is one option for sealing the intersection of drywall at the top plate, using a foam
seal. Hereís what it looks like being applied.
Another option for this detail is spray foam. We care more about the what, not how. Most
products and solutions are permissible under the specifications, as long as they address
the intent of the guideline. Hereís a photo of the sealing from the top
that was done on a retrofit application. Then ENERGY STAR requires insulation R-value
(quantity) and prescribes installation measures (quality) for the home. EPA is material and
product neutral, so it does not matter what material you use, as long as it meets these
two requirements. EPA seeks to avoid gaps, voids, compressions, and misalignment in insulation.
The insulation must be installed to RESNETís Grade I level. The only exception is when
rigid insulated sheathing is installed, the inside wall may have Grade II installation.
A very critical application is the band joist. This is almost impossible to achieve Grade
I using fibrous insulation batts, so EPA recommends spray foam insulation here.
There are also pre-made assemblies sold by some Structural Insulated Panel manufacturers
for band-joist applications. Here is a good example of insulation and blocking
applied below an above-garage bonus room. As you can see, it takes a lot of insulation
to fill these spaces. Another option for filling these spaces is
spray foam. Another option is Structural Insulated Panels,
which will ensure r-value and full alignment at the floor.
Another key place to get the installation right is the openings between the home and
the attic. Here is a large thermal hole. A common solution is adhering batt insulation
to the back of the hatch and applying proper gasketing and weather stripping around the
perimeter. The only concern with this method is longevity.
Another way to go is rigid insulation, which is more durable than the batt.
They also make Structural Insulated Panels specifically for the purpose of an attic hatch.
We also mentioned the importance of slab-edge insulation in completing the thermal enclosure
system. You can apply insulation to the inside as shown here.
You can also bevel the edge to ensure a proper surface for interior flooring materials to
go in. Or you can put the insulation on the outside
and use a protective layer like fibrous cement board or metal flashing piece.
We expect insulation on the outside when using a post-tension slab.
Air barriers are critical for insulation performance as well. Hereís an image of an attic kneewall
where we expect a solid air barrier such as OSB, sheet rock, or thinboard sheathing.
Air barriers are also critical where construction details leave exposed insulation as with behind
a tub or shower. Here you can see these details were coordinated so that both insulation and
an air barrier could be installed. In all climate zones, air barriers must be
installed with any dropped ceiling. Also required at the attic eave to stop wind-washing
of the blown-in insulation in the attic. Here, cardboard wind baffles were used as an air
barrier. If you often have severe weather, you may
consider using more durable products like foams and plastics.
Then, thermal bridging is addressed within a complete thermal enclosure system. There
are five options for handling this requirement at walls. One is advanced framing.
Hereís a detail where an interior and exterior wall meet. We need to make sure insulation
can go behind that assembly, using a lattice strip as shown here, or using other details.
You may also leave a gap between the studs, allowing sheetrock to slide behind. There
are many ways to achieve the intent of the requirements.
Wall framing requires the use of wood only where necessary to allow for maximum R-value
throughout the home. In addition, insulated headers are required.
The other option is using rigid insulated sheathing on the outside.
The three other systems available are Structural Insulated Panels, double wall framing, or
Insulated Concrete forms. On top of wall assemblies, attic eaves must
be constructed to reduce thermal bridging. One way to achieve this is via raised-heel
trusses, which raise R-value by creating more space for full-depth insulation.
Another way to meet this requirement is using a high R-value plug above the wall to maintain
the required R-value as prescribed by climate zone.
The last part of thermal bridging is for raised platforms in the attic, for HVAC or walking.
The last part of the complete thermal enclosure system is the high performance window.
We have an amazing value proposition with Version 3 homes. Competing with existing homes
which are often as bad as the thermal image shown on the left, Version 3 homes offer a
complete thermal enclosed system as displayed on the right. This will become the standard
of quality that people expect when purchasing new homes throughout the country.
This takes us to the next system: HVAC quality installation. The requirements here address
the performance compromise we often find with high-efficiency equipment operating in a poorly
designed system. A detailed checklist for the contractor and the HERS rater ensure that
full performance potential is being reached by the equipment.
The HERS rater will ensure that ducts are installed properly without compressions, extended
lengths, and bends. The rater will also check that boots are attached
and air-tight, without large gaps where air can leak out.
Pressure balancing will be assured with a transfer grille.
Grilles are sometimes installed above the door, and have sound and visual privacy features
installed. Door manufacturers may also create pre-hung
doors with transfer grilles so that no additional installation is required.
The second way to pressure balance rooms is via jump ducts in the ceiling. These, however,
are two more penetrations in the attic that may compromise temperature control. The third
option is a dedicated return from the bedroom back to the air handler.
Ventilation is required in every home. This can be done with an exhaust-only system as
shown here. Another option is a duct that comes from the
outside of the home back to the central air handler unit to provide fresh air supply.
The downside of these two systems is that air must be made up through holes and cracks
in the home. This doesnít offer complete air control, but is lower cost.
More expensive balance systems like energy recovery and heat recovery ventilators are
available. In addition, spot ventilation is required
in bathrooms and kitchens. Filtration installed to at least MERV 6 is
required, with installation that will not allow air to bypass the filter.
Whatís revolutionary about Version 3, is that for the first time, we can approach the
HVAC industry and say that standards that have not been followed per status quo can
now be followed with complete confidence, allowing properly sized systems to be installed.
The value proposition for HVAC, is that homeowners will finally get what they pay for. Theyíll
get something that everyone buyer deserves: comfort. Lastly, fresh, filtered air will
be available in every home. This takes us to the last system in Version
3: Water management. The first part of this is water-managed roofs, including heavy membranes
at all penetrations and valleys. In cold climates, we require membrane materials
to extend inside, up the roof, which is critical because of the extra abuse in cold climates
with snow and ice. In addition, any exposed roof sheathing should
be equipped with drip flashing. At walls, kick out flashing is required so
water is diverted away from walls. Advanced materials like premade plastic diverters
exist for this. Every window and door must have pan flashing
materials installed. There are pre-made plastic pans for this purpose.
And then every wall must complete the picture with a complete weather-resistant membrane,
properly coordinated with the windows and draining completely to the ground.
This can be done with house wrap, or with building paper.
Rigid insulated sheathing used to meet the thermal bridging specifications can often
be taped and act as an exterior weather resistant membrane as well.
At the foundation, the drain tile must be wrapped with a fabric filter in certain climate
zones. You can assemble this in separate pieces. You can also use a pre-made drain tile that
comes with a fabric filter wrapped around it.
Version 3 also specifies a capillary break under the slab for homes built in wet climate
conditions. For slab-on-grade construction, the gravel is exempt, but the plastic capillary
break is required. Crawl spaces must also be lined with a capillary
break. One of the benefits of this capillary break of gravel
and poly is that it serves as the first step toward an effective radon-resistant system.
Extensive amounts of homes in the US are exposed to high levels of radon.
Lastly, the home must be drained so water runs away from it.
On the inside of the homes, materials must be selected and used properly. This image
shows a vinyl wall covering in a hot humid climate which traps the hot air trying
to come into the home and leads to mold and mildew problems.
Protection of materials in wet climates is required so they donít go into the home already
moldy and wet. Because of these new requirements, Version
3 homes offer better protection for the largest investment of a lifetime, require less long-term
maintenance, and due to the prevention of mold and moisture problems, offers a healthier
environment for owners. In any home, we want to keep the inside temperature at a conditioned 70
degrees. Because of the thermal bridging in existing homes, much more energy is used to achieve this constant temperature,
and often comfort issues arise. Also for Version 3, water protection (for roofs, walls, foundations,
etc.) is a system and offers a complete break to
the outside environment. This is an incredible value package for
every homeowner, and will take new home construction to the next level.
Join us in
this program, and continue working with ENERGY STAR as its value continues to increase. Thank
you
for your interest in Version 3.