Tag Archives: Sustainability

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!

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.

Egress and Home Safety

MINOLTA DIGITAL CAMERAEgress is a means of emergency escape. Not surprisingly, all houses need egress for events such as a fire, and emergency egress is required by the International Residential Code for residential buildings. The IRC requires a form of egress in basements and rooms where people sleep. Each bedroom must have its own emergency exit.

While egress could be a door opening to the outside, it is most commonly a window, and the IRC specifies minimum requirements for egress windows. For one, an egress window needs to open to a public street, alley, yard or court. Also, the window must meet minimum size requirements so people can exit. The minimum size is 5.7 square feet, unless the windowsill is on the floor, in which case the minimum is 5 square feet. The window must be at least 2 feet tall and 20 inches wide. Meeting the minimum height and width requirements doesn’t guarantee meeting the minimum area, so the window will have to be larger in at least one of those dimensions.

Finally, the window cannot be more than 44 inches from the floor, and people must be able to open the window without any special tools or knowledge. Window coverings, such as a screen or bars, are OK, but people need to be able to remove them without any special force, tools or knowledge.

Basements are often located below grade, or below the typical ground level. Since egress windows in basements wouldn’t do much good opening to soil, a window well is required outside the window. The window well should be large enough for the window to open fully, and also should contain a ladder if the well is more than 44 inches deep. Of course, the IRC specifies well and ladder dimensions if this situation applies to your home.

Does your house have emergency egress? Some older homes built before the IRC requirements do not. A means of egress is sometimes overlooked during remodels — for example, converting a space to a bedroom that was not initially planned for that use. If you have a room that does not meet the minimum egress requirements, there are many reasons to correct the problem, the most important being providing a way to exit a house safely in an emergency.

Adding egress windows in required rooms will allow your house to pass inspection should you decide to sell it and will add value to the home as well. Sometimes, adding or replacing windows can become a major project, and it must be done correctly to avoid air leakage and drainage problems later. If you need to install egress windows, find a contractor familiar with the building code and who will take the time to properly install energy efficient windows that meet the requirements.

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

How can I use thermal storage in my home?

 A 5,000 gallon tank acts as thermal storage in a home heated by a solar thermal system. Photo Courtesy Reina LLC.

A 5,000 gallon tank acts as thermal storage in a home heated by a solar thermal system. Photo Courtesy Reina LLC.

CCHRC recently completed a study on how you can use thermal storage as part of your home heating system.

Thermal storage has recently gained interest in Alaska as it has the potential to increase the efficiency of heating appliances, enhance the use of renewable energy in cold climates, and reduce emissions of certain appliances like wood boilers. It is most suited for renewable energy systems such as solar thermal, geothermal and biomass, but can be adapted to a wide variety of heat sources. The report looks at different design considerations and describes several examples in homes around Alaska.

Thermal storage is a common concept. Many households use water storage tanks to provide domestic hot water, which can range from just a couple gallons to more than 100 gallons. Thermal storage also can be used in space heating systems to store heat for a certain period of time. For example, storing the heat from solar collectors in a buffer tank to use at night; storing heat from a wood boiler in a water tank to allow for a hotter, more efficient burn; or storing heat in the ground to harvest later with a ground source heat pump. In each case, thermal storage can be thought of as a “heat battery” because it holds energy to be used later. In this way, it can enable a heat source with intermittent delivery (like the sun or wind) to still meet demand.

Every thermal storage system needs three basic components: a heat source, a storage medium to store the heat (such as a tank of water, rocks or soil), and a discharge method (heat exchanger) to distribute the heat. Technically, any heat source can be used to charge a thermal storage material, however you should select the fuel and storage material based on availability, cost and compatibility with your home’s needs.

Also, many factors will drive the design of a thermal storage system for your home — such as your heating appliance, your distribution system, your heating demand, your lifestyle and many others. The design of the system also will depend on whether the system is being installed in a new home or being retrofitted into an existing one, as retrofits must accommodate the existing distribution system and available space in the home.

There are various applications of thermal storage throughout Alaska. A net-zero heating home built in Fairbanks several years ago uses solar thermal collectors and a masonry heater to charge a 5,000-gallon insulated water tank that provides heat to a radiant floor system.

The tank also heats domestic hot water in the house.

A different system, located at CCHRC, uses a wood-fired boiler to charge an insulated 1,500-gallon tank of water in the lab. The goal was to fire the boiler hot and fast, which produces more Btu and fewer emissions, and save the heat to use when it’s needed, rather than damping down the boiler so the fire lasts longer.

The water tank heats 1,900 square feet of lab space in the building. The tank was sized to hold as many Btu as the boiler could produce in one firing per day and to provide enough heat for the entire lab over a full winter day.

If you’re considering a thermal storage system, the first step is to consider what your goal is. Do you want to use renewable energy instead of fossil fuels? Are you looking for short-term (a few hours or overnight) or seasonal storage? Systems that are recharged daily are smaller and less expensive than seasonal systems.

Check out the report for an overview of various types of systems used in cold climates, case studies in Alaska, and tips for designing your own system.

Report: www.cchrc.org/docs/reports/thermal_storage.pdf

UAF Sustainable Village Week 18: Interior finishing

It’s finishing time at the Sustainable Village! The devil is in the details, and we’re detailing ceilings, floors, corners, railings, trim, and everything else. The time lapse shows workers installing beautiful birch paneling on the upstairs ceiling as well as cabinets and appliances.

UAF Sustainable Village Week 17: the first cellulose REMOTE wall

This week we tried a new building system at the Village–a cellulose REMOTE wall in the SW house. A REMOTE wall has the majority of the insulation value, or R-value, outside the sheathing rather than inside. Up to this point, we always used rigid foam on the exterior. But since one goal of the Village is to test new techniques for both cost and energy use, we decided to try a REMOTE wall with batts as interior insulation and 9 inches of cellulose on the outside.

The house has two sets of studs, with sheathing applied to the inner wall. The inside wall cavity is filled with a recycled batt insulation. The outer wall was wrapped in Tyvek. To insulate the outside wall cavity, we hole-sawed a 6-inch hole in the sheathing in each wall bay (on both floors) and sprayed in 12 inches of dense-pack cellulose. Those holes were patched with poly sheeting and acoustical sealant. The whole wall is 18 inches thick.

We also installed birch paneling ceilings, cabinetry, and ventilation systems in 2 of the homes. The homes are mostly sided and are starting to look very livable!

UAF Sustainable Village Week 12: blown-in cellulose and windows

During Week 12, we insulated walls of the second house with six inches of fiberglass batting on the inside and 8 inches of foam board on the outside. We also blew two feet of cellulose insulation into the roof of the first two homes. Cellulose is made from recycled material like newspaper and cardboard.

We also began installing windows in the homes. All windows are triple-pane, low-e argon filled, designed to minimize heat loss and avoid condensation in an extreme climate.

Each home will be sided with a different color combo, with a mix of metal siding and recycled steel pipe.