Tag Archives: energy efficiency

A Holistic Approach to Sustainable Northern Communities

The First Roundtable on Holistic Design at CCHRC in Fairbanks, October 2014.

The First Roundtable on Holistic Design at CCHRC in Fairbanks, October 2014.

Tens of millions of dollars are spent each year on housing and infrastructure to improve quality of life in rural Alaska – wind turbines, power houses, roads, housing, weatherization, plumbing, and much more. Meanwhile, many Alaska communities are struggling to survive in the face of energy costs, climate change, coastal erosion, lack of jobs, and other challenges.

Plenty of organizations are trying to help – state and federal agencies, regional corporations, housing authorities, tribal entities, nonprofits – each focused on an individual aspect: energy, housing, sanitation, transportation, health, local economies, culture, education. Yet rarely do we address all these pieces in a holistic approach. The evidence is everywhere: brand new $70,000 sewer lines hooked up to rotting houses; leaky homes in villages that pay $8 a gallon for heating fuel; roads built one year and dug up the next to install water pipe.

Jack Hebert with CCHRC talks about the role of energy efficient housing and indoor air quality in community development.

Jack Hebert with CCHRC talks about the role of energy efficient housing and indoor air quality in community development.

The Holistic Approach to Sustainable Northern Communities is a demonstration project that will factor in the many elements of community development. It started with two roundtable discussions this fall, where leaders from all levels of government and community planning came together and shared their successes and challenges, their needs and ideas for a more effective process. Now we are planning a pilot project in the Yukon Kuskokwim region that starts with one piece and builds a model of collaboration for all communities in Alaska.

Stay tuned for our next roundtable in Anchorage in December!

Moisture Performance of Cellulose Insulation

Blowing dense-pack cellulose insulation into the test walls.

Blowing dense-pack cellulose insulation into the test walls.

Building envelopes have a hard job in Interior Alaska—keeping us warm, dry and healthy at 40-below. CCHRC tests a variety of building designs and products to see how they can be applied in this environment. We recently studied the moisture performance of cellulose insulation to see how it compared to other common types, like fiberglass and rigid foam, and how it performed in a super-insulated house.

First, let’s look at a conventional wood-framed wall with 2×6 or 2×4 studs and an interior vapor barrier. This system has historically worked in the Interior because the vapor barrier limits the moisture allowed into the walls and moisture that does sneak in remains frozen through most of the winter. During the spring, the walls thaw and dry to the outside.

But when you add exterior foam insulation to a house, a common retrofit technique to save energy, the walls can no longer dry to the outside. Is this good or bad for the wall? Depends on how much you add. If you add enough exterior insulation (for example, six inches of EPS foam for a 2×4 wall) the sheathing and framing will stay warm enough to avoid condensation, improving your overall moisture control. If you don’t add enough, however, you move your wall sheathing into the danger zone—above freezing and very humid.

We’ve learned from earlier studies how to use fiberglass and EPS and XPS foam in various wall systems to improve energy efficiency while avoiding moisture problems (See cchrc.org/safe-effective-exterior-insulation-retrofits). This latest study looked at how cellulose performed in different wall scenarios over an 18-month period. These were not standard walls—they intentionally lacked a vapor barrier because we wanted to force moisture into the walls.

Cellulose insulation is made primarily of recycled paper. As a local, rather inexpensive product, it has recently become more popular in building in Interior Alaska. “Dense-pack” cellulose is blown into a wall to a density of 3.2 pounds force per cubic foot, which is designed to prevent the insulation from settling over time. Dense-pack cellulose has an R-value (or insulation value) of 3.7 per inch—slightly higher than fiberglass batts and slightly lower than EPS foam.

Our study shows that cellulose can handle moisture better than fiberglass or EPS insulation when used properly. The test wall that used cellulose as both interior and exterior insulation maintained lower humidity levels (and was less likely to condense or grow mold) than the test wall that used interior fiberglass and exterior foam.

That can be partly attributed to material properties of cellulose. Dense-pack cellulose is actually less permeable to air flow than fiberglass batts. So when used as interior insulation, it reduces the amount of moisture that migrates into the stud cavity.

Cellulose also has the ability to absorb and release water vapor, allowing it to moderate moisture levels within a wall and prevent the large spikes in relative humidity that cause moisture damage.

It’s also more permeable to water vapor than EPS or XPS.  The test wall with exterior cellulose had lower humidity levels than the wall with exterior foam, because it allows faster drying to the outside.

Based on this study, dense-pack cellulose can provide a good option for exterior insulation beyond rigid foam board. In future studies we plan to look at the minimum amount of exterior cellulose needed to keep the sheathing warm and dry.

What are Structural Insulated Panels and considerations for Alaska

SIPsStructural Insulated Panels, or SIPs, are prefabricated building panels that combine structural elements, insulation, and sheathing in one product. SIPs can be used for the walls, roof and floor of a building in place of more traditional construction methods, such as stick-framing. A SIP typically consists of a foam insulation core with a structural sheathing panel bonded to both faces. Sheathing panels are usually made of industry standard OSB or plywood.

Building with SIPs

 

Constructing a home from SIPs begins at the design phase: builders must work with the SIP manufacturer since the panels are specific to the design. Once the plans are finalized, the SIPs are made and shipped to the job site. The panels are labeled so builders know exactly where each panel goes in the building.

As they are erected, the panels must be joined together according to manufacturer specifications. For instance, many panels are joined with splines that are secured with screws. When the structural connections between panels are being made, workers must take care to seal the joint between the panels to ensure it remains airtight. Air sealing the panel joints can be accomplished using sealing agents such as caulk, adhesive, mastic, spray foam or tape. A tight seal is also necessary in order to prevent moisture from entering the panel, which can lead to structural deterioration of the panel components over time. Some building inspectors may require a 6mil polyethylene sheeting vapor retarder be installed on the interior side (warm side) of the SIPs once the panel construction is completed.

SIPs2

Electrical outlets and wiring are usually installed into recesses and holes pre-cut into the panels, both on the interior and the exterior as needed. Any special considerations for running electrical systems or other mechanical penetrations through the SIPs should be addressed with the manufacturer during the design phase.

Benefits and Concerns

There are several potential benefits to building with SIPs. For one, the absence of an air permeable wall cavity prevents convective heat losses from occurring within the panels. Large panels will have fewer framing members than a stick-framed wall, which reduces heat losses due to thermal bridging. With a trained crew, SIP buildings can be erected quickly, a big advantage in climates with short building seasons. Properly constructed, a SIP panel home can realize a high level of air tightness and energy efficiency.

On the other hand, builders must take extra care to ensure proper assembly and sealing to prevent any problems due to moisture infiltration and air leakage. Builders also do not have much flexibility in on-site design changes, since panels come pre-cut. An experienced builder who can work through a home design with the manufacturer and who doesn’t cut corners with sealing panel joints is a necessity.

SIPs can be either cost-effective or cost-prohibitive depending on the situation. The design services and shipping costs may drive the price of SIPs above that of conventional framing materials. However, this can pay off in reduced labor costs if a trained crew erects a building quickly, or if several buildings of the same design are being erected.

Valuing energy efficiency in the housing market

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The Alaska Housing Finance Corporation recently released a tool that could boost the appraised value of energy efficient homes.

The AK Appraisal Tool, developed by AHFC, the Cold Climate Housing Research Center and Alaska Craftsman Home Program, allows appraisers to add value to a home that performs better than comparable homes. The tool could promote energy efficient housing through making efficient homes more affordable and increasing their resale value.

Appraisers typically look at factors like square footage, number of bedrooms and aesthetic features like granite counter tops. If a house was super-insulated or used alternative energy sources, there was no accepted way to factor that into the appraised value. This tool provides a way to value energy efficiency based on the energy bills of a house compared to other similar houses in the area.

Here’s how it works

You log onto the site  and enter basic information about a house, including the community, the energy bills and at least two of the five following pieces: street name, number of bedrooms, square feet, rating points and year built. Our 1,800-square-foot test house was located in Fairbanks and had $6,000 in annual energy costs, including heating oil and electricity. The program then searches AHFC’s database of 105,000 housing units to find all comparable homes in the same area — in this case 85 — and calculate their average utility bills — $8,150. You can enter up to 10 other comparable houses (based on other appraisals). The program crunches all this information into the “net present value,” or the energy savings of the test house versus an average house during a 5-year period — $9,058. The appraiser can add up to that amount to the value of a home (all appraisals must be reviewed and accepted by the lending institution).

The program also provides the impact to the mortgage payment. In this example, if $9,058 were added to the home’s appraised value, it would increase the monthly payment by $44 (based on a 30-year mortgage at 4.25 percent). But remember, the homeowner is saving $2,100 per year, or $180 per month, in energy compared to an average house, so the overall savings far outweighs the bump in the mortgage payment. Plus, the resale value of the energy efficient house is higher.

There are benefits to the lending institutions as well. The fact that homeowners are spending less on energy every month increases their chance of making their mortgage payments. This reduces the lender’s risk of default and foreclosure.

How will it be used?

AHFC is already training lending institutions, builders and realtors to use the tool.  Builders could also use it to show clients the potential energy savings and increased appraised value of an energy efficient house.

Thermal mass and passive solar design

In construction, thermal mass refers to heavy, dense building components with a high capacity to absorb, store and release heat, for example—logs, masonry, concrete and adobe.  These materials are used in the building envelope to provide structure, but their thermal properties mean that they can also provide other benefits. In this first article of a two-part series on thermal mass, we’ll address how thermal mass can be combined with passive solar design to reduce building heat and cooling load.  Next week we’ll examine the effect of thermal mass for more conventionally designed homes in three different locations.

Passive solar design uses a combination of building features along with the sun’s energy to provide heating in a home.  Typically, a home’s orientation combined with south-facing windows and a large thermal mass are designed to collect, store and distribute solar energy during the heating season. During the summer, features such as deciduous trees or awnings can block solar energy from entering a house and causing overheating. Many homes in Alaska use passive solar design to provide part of their heating needs during the year.

In passive solar design, there is no control system that dictates the movement of heat energy, as with a boiler or furnace.  To understand how this might work, picture a house with a concrete floor in a south-facing room on a sunny spring day in Fairbanks.  As sun’s radiation enters the room through the windows, it warms up the room and the thermal mass of the concrete floor absorbs this energy throughout the day.

ThermalMass_graphic

At night, the situation reverses.  With no incoming solar radiation, the heating system will need to work to keep the temperature of the room at the set point. However, as the room’s ambient temperature drops below the temperature of the thermal mass, the stored heat energy in the massive floor radiates back into the room, stabilizing the temperature and delaying when the heating system needs to switch on. In effect, the thermal mass acts as a heat battery, storing solar radiation until the sun disappears and then releasing it back into the room. A properly designed passive solar system can result in energy savings for a home because the thermal mass can store excess heat during the day and allow it to offset nighttime heating loads.

Although thermal mass is often in the form of a concrete floor, there are other ways to incorporate it into a home—such as a wall that receives lots of sun or a masonry bench or shelves in the sun’s path.

As the days lengthen during the spring and summer, the large south-facing windows in the above example can allow too much solar radiation to enter a room and cause it to overheat. Some people install awnings or curtains, or plant deciduous trees to shade the windows. Thermal mass also helps prevent overheating, especially in early spring before deciduous trees have leafed out.  A room that might have become uncomfortably warm during the day instead experiences less rise in temperature as the solar radiation is absorbed by the thermal mass. This energy is released later in the evening when outdoor temperatures are cooler. Overall, the thermal mass acts to smooth out temperature swings in the room, enhancing indoor comfort.

 

 

 

Building workshops & classes this spring

While it might seem like summer is far away, the building season is right around the corner, and now is a good time to finalize any plans for upcoming home improvements. If you’re interested in reducing your home’s energy use, there are several opportunities this spring to learn about energy efficient building and retrofit techniques.

The building addition at CCHRC, which opened last year, features passive solar design, radiant floors, a pellet boiler and a super-insulated building envelope. There are efficient technologies in the original building as well, including a masonry heater, ground source heat pump, a sewage treatment plant, solar photovoltaic panels and thermal storage. Tours are offered at 2 p.m. on the second Thursday of every month and feature both the original building and the addition, and include plenty of time for questions and discussion, as well. Spring 2014 tours will take place Feb. 13, March 13, April 10 and May 8. In addition, the Builders Resource Library at CCHRC contains information on many aspects of cold climate construction and heating systems. The library is open Monday-Friday, and a catalogue is available online atcatalog.library.uaf.edu (select CCHRC from the Library menu).

Golden Valley Electric Association offers one-on-one instruction through its Home$ense audit program. Through the $40 program, an energy auditor visits your home to discuss ways to reduce your electrical usage and energy costs. To sign up, call the member services department at GVEA at 458-4555 or visit www.gvea.com.

Classes on more advanced topics are offered by the Alaska Craftsman Home Program (ACHP). Advanced Cold Climate Construction will be held Feb. 12 and 13 in Fairbanks, covering the latest energy efficient construction methods on topics such as insulation, vapor retarders, windows and ventilation. The class includes a construction manual and certificate for continuing education credits. Also, ACHP will

offer a one-day class on the Building Energy Efficiency Standard (BEES) on March 19 and May 22. This class covers the BEES requirements for insulation values, air leakage, moisture protection and ventilation. Fees and registration for these classes and more information can be found at www.achpalaska.com.

For those interested in wood heating, UAF is hosting the Firewood Workshop from 10 a.m. to 2 p.m. Saturday in the Bunnell Building. The workshop covers how-to tips for cutting and drying wood, operating a wood stove and more.

Finally, the annual Interior Alaska Building Association Home Show will take place March 28-30 at the Carlson Center and will feature topics including financing, remodels and new construction. There also will be seminars and demonstrations on a variety of topics related to homebuilding. The home show kicks off the summer building season in Fairbanks and is an excellent way to gather lots of information about energy efficiency.

How can I prevent window condensation in the winter?

Windows can be a barometer for how much humidity is inside the home.

Windows can be a barometer for how much humidity is inside the home.

On really cold days, you may notice condensation forming on the inside of your windows. This can be caused by one or a combination of factors: excess humidity, inadequate ventilation, or poor windows. To understand and correct a particular issue in your home, you need to know some basic properties of moisture.

Condensation occurs when water vapor (a gas) turns into water droplets as it comes into contact with a cold surface. The point at which this happens (called the “dew point”) depends on the temperature and humidity of the inside air. The warmer the indoor air, the more water vapor it can “hold,” and moisture can better remain in the vapor state. When air moves next to a cold window, the temperature drops and it can’t “hold” as much vapor.  That’s when you start to see condensation forming.

 

For example, if the indoor temperature is 70 degrees and the outdoor temperature is 0, then moisture will begin to condense on a single-pane window when there is roughly 15 percent relative humidity in the house. A double-pane window will cause condensation at around 25-40 percent relative humidity, and a triple-pane window at between 30-50 percent.  These are rough numbers are based on average window insulation values.

The recommended indoor humidity levels for occupant health and comfort range from 30-50 percent. The general rule in a cold climate, however, is to target the lower end of this spectrum due to the risk of condensation within walls and ceilings. If your house has adequate mechanical ventilation, humidity is less of a concern. In Fairbanks, it’s tough to maintain anything close to 50 percent humidity in a properly ventilated house, because the winter air is so cold and dry.   Because of its low moisture content, the inherent dryness of Fairbanks winter air is good for homes but not always the occupants, since the dryness can cause discomfort.

What can I do about it?

Three things: make sure your home is properly ventilated, aim for less than 40 percent relative humidity to keep both you and your home healthy, and consider replacing your windows or adding moveable window insulation during cold months.

If you already use mechanical ventilation and have low interior humidity, but are still having problems, you may need to examine your ventilation setting. If you have a heat recovery ventilator (HRV), it may be recirculating too often, which can contribute to increased moisture build up in the air. Recirculation mode closes the connection to the outside and brings exhaust air back into the rooms.  Recirculation mode keeps the HRV core defrosted and saves energy, but sometimes it can run too long.  Some experimentation with the HRV settings may be necessary.   For example, in 20/40 mode the HRV brings in fresh air for 20 minutes and then recirculates for 40 minutes, and likewise for 30/30. If you’re getting condensation in your current mode, try decreasing the amount of time the unit recirculates.

Also make sure air is allowed to circulate—either passively or mechanically—throughout the entire house. If you close the door to the bedroom, the air can become cold and moist enough to condense on windows.

Older, poorer performing windows can create problems no matter what you do to your interior air. Bad seals around operable windows, metal spacers between the panes, and inadequate insulating value can cause the window surface to get cold enough for condensation to occur.  If you’re not ready to invest in new windows, consider some type of moveable window insulation like foam board (on the outside) or well-sealed plastic film (on the inside). A CCHRC guide to different types of window insulation can be found at

http://www.cchrc.org/evaluating-window-insulation.

 

UAF Sustainable Village Cuts Energy Use in Half

The Birch House at the UAF Sustainable Village used the equivalent of 367 gallons of heating oil in the first year of occupancy, less than half as much as an average home its size in Fairbanks.

The Birch House at the UAF Sustainable Village used the equivalent of 367 gallons of heating oil in the first year of occupancy, less than half as much as an average home its size in Fairbanks.

The Sustainable Village homes at the University of Alaska Fairbanks are a new model of energy efficient, affordable housing for Interior Alaska. The four 1,600-square-foot homes were built at the university in 2012 to demonstrate that super-efficient, climate-appropriate houses could be built without breaking the bank. University students helped design and build the homes, adding their own ideas about sustainable campus living.

The homes incorporate experimental techniques, like solar hydronic heating and adjustable foundations on permafrost, that should reduce energy costs and improve the durability of the homes. CCHRC, along with student residents, have been monitoring the energy use and indoor air quality at the homes for the past year.

On average, the homes used less than half as much energy as an average new house in Fairbanks. The lowest user was the Willow house, going through the equivalent of 366 gallons of heating oil No. 1, or 48.3 million Btu, for both heating and domestic hot water from September 2012 to September 2013. The average same-size house in Fairbanks uses about 920 gallons, according to the Alaska Housing Finance Corporation’s database. Even the average new energy efficient house uses about 660 gallons per year. That’s more than the biggest energy user at the Village, the Spruce House, which used only 463 gallons of oil equivalent.

How do the homes save energy?

The homes are super-insulated and incorporate energy-saving features like heat recovery ventilation, triple pane windows and Energy Star appliances. The Willow House has a REMOTE wall with 8 inches of exterior foam insulation and 3.5 inches of fiberglass batts inside the wall cavity (for a total of R-51). That’s more than twice the insulation value of a conventional 2×6 wall with 5.5 inches of fiberglass insulation. Space heating and hot water are provided by a propane boiler and three solar thermal collectors.

The Spruce House, on the other hand, has a double wall filled with 18 inches of cellulose insulation (R-64), and a forced air heating system with a small diesel heater that heats fresh ventilation air.

Because each house has roughly the same heating load, the difference in energy use can be largely explained by the differing mechanical systems and the occupants themselves. What’s the set point of the thermostat? How long are the showers in use?

A cost analysis showed the Sustainable Village homes were competitive with other energy efficient building in the Interior — averaging about $185 per square foot, including water and wastewater, electrical, and roads (not including land).

CCHRC also monitored soil temperatures at the homes to study the effects of different foundations on the ground. The two western homes are built on permafrost, or permanently frozen ground, only 2-3 feet deep in the summer. The trick when building on permafrost is to isolate the house from the ground, so heat doesn’t leak into the soil and thaw the frozen ground (which can cause expensive structural problems). These homes used experimental foam raft foundations, steel floor joists with a thick layer of polyurethane spray foam designed to protect the permafrost.  Sensors underneath the house show that the foundations are working so far: the temperature at 4 feet deep has risen less than 5 degrees, and at 24 feet has remained the same.

See the full report on first year performance of the homes here.

Arctic Wall is a new energy efficient construction option in the Interior

The Arctic Wall is an airtight double-wall system using cellulose insulation and is designed to allow water vapor to diffuse through the wall.

The Arctic Wall is an airtight double-wall system using cellulose insulation and is designed to allow water vapor to diffuse through the wall.

CCHRC recently tested a wall construction technique in the Interior that provides very high levels of insulation to maximize energy efficiency. The Arctic Wall is an airtight double-wall system using cellulose insulation and is designed to allow water vapor to diffuse through the wall.

The system was designed by Fairbanks builder Thorsten Chlupp and uses some of the principles of the REMOTE wall—another super-insulated building technique that places the majority of the insulation outside the load-bearing wall.

Conventional cold climate construction calls for a vapor retarder on the warm side of the exterior wall.   This vapor retarder typically consists of a layer of tightly air-sealed 6 mil polyethylene plastic sheeting, which keeps water vapor generated in the living space in winter time from getting into the exterior wall cavities.  Installing a traditional plastic vapor retarder properly requires a high level of detail around all penetrations to prevent air and moisture movement through the wall assembly. This is a known weak spot for conventional cold climate construction.

The Arctic Wall, on the other hand, has no plastic vapor retarder. Instead of stopping moisture movement with a barrier membrane, it works by remaining permeable so water vapor can move through the wall with the seasons, creating a super-insulated wall that can also “breathe”.

The key components of the Arctic Wall include:

  • an extremely tight building envelope to prevent air leakage and moisture transport via air leakage through the wall
  • the majority of the insulation outside the structural framing and air barrier
  • a wall that is open to water vapor diffusion that has enough capacity within the insulation to absorb and release a heating season’s worth of water vapor without succumbing to moisture damage

Chlupp’s system under study by CCHRC contains a 2×6 interior structural wall filled with blown-in cellulose with taped sheathing and a vapor-permeable air barrier (Tyvek HomeWrap) wrapped on the outside of that sheathing. Spaced a given distance depending on desired insulation thickness from the 2×6 inner structural wall, a 2×4 exterior wall is installed and wrapped around the outside with another air barrier membrane.   The space between the two walls is then filled with 12 more inches of blown-in cellulose. See diagram for details.   Depending on thickness, a superinsulated wall of this type can attain R-values of 70 or more, more than three times a traditional 2×6 wall system,

CCHRC monitored the Arctic Wall’s performance over 13 months by placing temperature, moisture and relative humidity sensors in the walls.  The goal was to determine whether the conditions would support mold growth, and how moisture would move through the walls.

Test results indicated that both temperature and relative humidity levels in the walls were not sufficient to support mold growth. Neither side of the air barrier covering the exterior of the 2×6 structural wall ever approached the dew point (the point at which vapor condenses to water), indicating the structural framing is well protected from moisture.

The relative humidity of the bathroom wall (the one likely to see the most moisture) never exceeded 65%,  staying well below the risk level for mold growth.

CCHRC also used moisture modeling software to predict how the walls would perform over a 9-year period, which showed that humidity levels and moisture content within the walls should not reach a level where mold growth would be a concern.

Also noteworthy was the direction of moisture transport in the Arctic Wall—walls dried to the inside in the summer and to the outside in the winter. This is not possible with conventional cold climate construction.

The Arctic Wall is a specific system whose components must be carefully engineered and built to ensure proper performance and moisture management.  Based on CCHRC testing, the Arctic wall has done very well in Interior Alaska and provides a new option for a super-insulated house design.

Read the snapshot and full report on the CCHRC website at http://cchrc.org/arctic-wall

New videos on mitigating radon in your home

How to mitigate radon in new construction

The hilly areas containing fractured schist and rock around Fairbanks are known for having high concentrations of radon. A good radon mitigation system will ensure healthy indoor air quality. Your single best chance at dealing with radon issues is during new construction.

In this video, Ilya Benesch, building educator at the Cold Climate Housing Research Center, demonstrates the essential steps of installing a radon mitigation system for a slab-on-grade foundation.

The video follows EPA guidelines for installing radon mitigation systems found here:

http://www.epa.gov/radon/pdfs/buildradonout.pdf

 

Examining a radon mitigation system

In this video, Ilya Benesch visits a construction site and explores how the contractor has installed a radon mitigation system.

 

The project was funded by the University of Alaska Fairbanks Cooperative Extension Service. For more information about radon, visit: www.uaf.edu/ces/energy/radon.