Making Houses Work

See a sneak preview of CCHRC’s Air Source Heat Pump presentation to be given at the Rural Energy Conference in Anchorage in May. Building Science Research Director Colin Craven outlines some of the opportunities and hurdles for air source heat pumps in Alaska.

More info on the conference here
More info on air source heat pumps here

Schematic of the BrHEAThe system being used in the Buckland prototype house.

In the north lab is a prototype heating system that locks together heating and ventilation—two crucial elements of life in Alaska.

CCHRC researchers developed the integrated heating and ventilation system, called BrHEAThe, to ensure that new energy efficient homes are getting ample fresh air.

As homes are being built tighter in Alaska to save energy, less air is able to leak into or out of the building, so things like water vapor and chemicals generated from cooking or furniture can be trapped inside. Without ventilation, these can build up to harmful levels for both occupant health and building durability.

Some occupants are wary of mechanical ventilation, such as fans or heat recovery ventilators (HRV), because they can replace heated air with cooler air. As a result, some homeowners turn off or disable their ventilation systems.

The BrHEAThe system marries together heating and ventilation so that incoming air is always hot and fresh.

Here’s how it works.

Fresh air comes in through the HRV and recovers some heat from outgoing stale air. Then it enters a filter box and passes through a heat exchanger, robbing heat from a loop that’s connected to a boiler.

“If we pump hot water through this heat exchanger, it’s going to warm the air that moves across the heat exchanger from 40 degrees to 140 degrees,” said research engineer Bruno Grunau.

The heated air is then distributed through ductwork throughout the home.

The high efficiency boiler also heats a domestic hot water tank.

During a test run in the lab, the system worked smoothly, raising cold supply air to a usable temperature: outside air came in at 25 degrees F and was raised to 58 degrees by the HRV. After passing through the heat exchanger, it was then dispersed into rooms at 139 degrees.

The BrHEAThe system will be deployed at a CCHRC research prototype home in Buckland that breaks ground this week.

“Because building envelopes are getting warmer, heat loads are being reduced. As a result, systems like this can now be used to meet heating requirements,” Grunau said.

Video of a test of the heating system.

If pilings are used on permafrost, they must be installed to a depth that will both support the structure and resist frost jacking due to seasonal ground movement.

Permafrost is loosely defined as soil and/or rock that remains frozen for more than two years. In the Fairbanks area, permafrost tends to be discontinuous and is concentrated primarily on north-sloping hills and in lower elevations with heavy ground cover. Big trees do not guarantee the absence of permafrost; it might just mean that permanently frozen ground or ice is down far enough that the soils in that spot can support a larger root system. The only way to be certain of what the ground contains is to have a soils test drilling done.

With permafrost, the safest bet is to it avoid it altogether and move to another piece of land. This is easier said than done, particularly because of the scarcity of buildable land near Fairbanks that is affordable. If you decide to build on permafrost, be as strategic as possible. Smaller and simpler structures will tend to fare better than larger, more complicated ones.

Minimal site disturbance is the accepted practice. The trees and the ground cover are your best friend. They protect and insulate the ground from the heat of the summer. A great example is the green moss you find on many of the shaded low-level areas in Fairbanks. Moss has a high insulating value, and in many cases if you dig down a couple of feet, the ground might still be frozen in the middle of summer.

Strategies for construction on permafrost include:

• As a general rule, the organic layer of ground cover provides insulation and should not be removed, as this will increase the risk of thawing any frozen ground underneath.

• Elevate and properly insulate the bottom of your house to prevent heat losses through the floor system from reaching the ground underneath, which can lead to thawing.

• In post and pad construction, use a thick gravel pad that is significantly wider than the house itself (also insulated if possible) to stabilize the ground and spread building loads.

• If wood or steel piles or helical piers are used, they must be installed to a depth that will both support the structure and resist frost jacking from seasonal ground movement.

• Cut trees sparingly to maximize site shading (while permitting for a fire break).

• Build a wrap-around porch, which will help shade the ground around and underneath the house.

• Incorporate large roof overhangs to shed water away from the house and provide shade.

• Install gutters and manage site drainage well away from the house.

• Retain an engineer familiar with local soils conditions to assist in designing a foundation system that will adequately and safely support your home on the soils specific to your site.

• Septic systems also must be engineered to function on permafrost, and remember that conventional systems might risk thawing the ground.

Other Resources 

Permafrost Technology Foundation case studies: http://www.cchrc.org/permafrost-technology-foundation-library

U.S. Permafrost Association website: www.uspermafrost.org/education/PEEP/ptf-manuals.shtml

UAF Cooperative Extension Service online publications at www.uaf.edu/ces.

Crawl spaces are an area of the house that tends to get neglected. The old adage “Out of sight, out of mind” might apply here. Unfortunately, this also means crawl space problems can go unnoticed until they have an effect on the living space above. At this point, a problem that could have been easily remedied might have progressed into an expensive structural or health-related issue. The crawl space also can present a significant hidden energy drain on a home if not insulated properly.

Good moisture control is of primary concern in a crawl space. This starts outside the building envelope, and many problems can be stopped here in their infancy.

Gutters are a relatively inexpensive addition to a house that can provide huge preventative paybacks. In a climate with lots of rain, a house without gutters can direct lots of water against its foundation. Soils, wood and especially concrete are good conductors of water through capillary action. Picture a paper towel soaking up water — concrete works this way and can carry water great distances. If gutters are not an option, then at minimum the soils around the house should be sloped to direct water away from the building.

Once water reaches the foundation, things get a lot tougher. The structure must be prepared to resist infiltration. Ideally, both concrete and wood foundations should have some form of waterproofing on the outside. If this has deteriorated or was never installed, this might need to be remedied.

Assuming all external sources of moisture penetration have been addressed, the next step is to inspect the interior. With few exceptions, exposed dirt floors should be covered and well sealed with a continuous vapor retarder such as polyethylene with a minimum 6 mil thickness. If the floor will receive traffic, then it might be necessary to use either thicker and/or reinforced polyethylene sheeting or an even more durable membrane such as EPDM rubber. Even a dirt floor that looks and feels “dry” can release significant amounts of moisture, especially after heavy rains.

Another important consideration is radon, a cancer-causing radioactive gas that occurs naturally in the earth. The University of Alaska Fairbanks Cooperative Extension Service advises that if you have never tested your crawl space or basement, cold seasons are the best times to do so. The negative pressures created by combustion appliances, and stack effect in winter time, can bring radon into the home at a higher rate. Although high radon concentrations are considered hazardous, it’s possible that remediation after detection can be relatively simple. Testing crawl spaces is strongly recommended in areas known to have soils with radon concentrations. Test kits and information are available through the CES at 474-1530.

How well a crawl space is insulated and sealed can affect the entire building envelope. In Fairbanks, building codes require foundations to be a minimum of 42 inches below grade to protect the footings from freezing and frost jacking. Anything above that point could be at risk for freezing during the winter. This can mean serious heat losses if the crawl space is under-insulated.

Inspect the foundation walls and floor system closely. If fiberglass insulation was set directly against the inside walls with no moisture protection, or the dirt floor was left exposed, it might be wet and need to be replaced. If the floor joists were insulated, the floor system should be looked at closely. Any exposed ducting should be inspected to make sure all seams are sealed and connected. Be sure that exhaust fan piping (such as dryer ducting) doesn’t just terminate under the floor, but vents directly outside.

If you need to add or replace insulation, rigid foam and spray foam are good options. These types have high R-values and also qualify as vapor retarders. If you use foam, especially below-grade, make sure it’s approved by the manufacturer for your specific application. Spray foam and foam board may have certain restrictions or limitations in crawl spaces because of local fire codes. Some brands of foam insulation might meet fire code at a given thickness, while others might not.

In addition, it might be possible to use either a coat of fire retardant paint, drywall or fiberglass insulation to protect the foam board if required. The best source of information regarding current fire code considerations for foam insulations can be found at the local building department. Keep in mind that typically the local fire codes will need to be met if the home is put up for resale and is subject to inspection.

Tomorrow would be a good time to peek under the floor. The crawl space is integral to the foundation of the house and, in some cases, the largest source of unregulated airflow into the home. It is not a good place to let moisture, poor air quality or bad insulation go unchecked.

There are many ways that manufacturers are increasing the energy efficiency of their products. You’ve probably seen the Energy Star rating on new appliances. Since 1992, the federal government has been giving tax incentives and rebates to manufacturers and/or consumers for making improvements like reducing the amount of water needed to wash a load of towels or the electric load of your refrigerator.

One way to reduce energy use is by using electronically commutated motors (ECM). This is a high-efficiency motor that can work in home systems like air handling and heat distribution (or cooling). ECMs allow the motor to run at different speeds, depending on the demand from the appliance, rather than maintaining one speed constantly. This type of motor has been in use in the U.S. since 1985 and uses as much as 67 percent less power than that used by standard motors (PSC). That’s because sensors in the motor determine the system’s need and provide just the amount of energy needed. ECM motors are also quieter and cooler than standard motors.

Radiant floors are one example. The ECM runs the pump that distributes hot water to heat your floors. A sensor in the system measures the temperature of the fluid in your system and tells the pump to run only as fast as it needs to to heat your rooms. When running most efficiently, a system using an ECM could use less power than a standard light bulb.

HRVs (heat recovery ventilation systems) are also now made with ECMs. Just as with the hot water circulator pump, the HRV’s motor will vary its speed (and therefore energy use) based on the demands from the building.

When you push your “booster” button in the kitchen, the motor will run the fan at a faster rate and exchange more air for a set period of time. When the HRV is operating at its normal (lower) level, it will use less power and run less forcefully.

While it is possible to have a professional retrofit your existing furnace, HRV or other appliance with an ECM motor, it is generally more cost-effective in the long run to purchase a new appliance. Some appliances are not configured to allow the conversion at all — the older it is, the more this is likely.

A new white paper by the Alaska Housing Finance Corporation gives the first in-depth picture of the energy use of public buildings in Alaska. By looking at comprehensive energy audits of 327 out of an estimated 5,000 public facilities, CCHRC researchers found that the average building can save $25,000 per year on energy just by modest investments in efficiency.

That adds up to $125 million annually in taxpayer savings. Many of these upgrades are easy and affordable.

Some examples found by AHFC energy auditors include adding occupancy sensors to lighting and ventilation systems, programming thermostats to lower the heat when buildings aren’t occupied and using digital controls to avoid over-ventilating building zones. Energy auditors also found many zero-cost ways to save energy by fixing operational issues such as turning off heat tape in the summer and shutting off backup pumps when they’re not needed.

The report shows Fairbanks buildings are the most energy efficient in the state, while the North Slope, Anchorage and Southeast (outside of Juneau) were the least energy efficient.

Surprisingly, there was no correlation between the cost of energy in a given community and the performance of buildings. In fact, many of the same types of buildings in the same climate consumed vastly different amounts of energy, highlighting differences in construction and operation.

“That’s further evidence that many building managers don’t know how their buildings are performing, because they’ve had no one to compare themselves to,” CCHRC researcher Dustin Madden said.

This report provides facility managers with reference points in their climate and region, and gives tips from energy auditors on saving energy.

While the paybacks of energy improvements are often quick, funding can still be a challenge. Some organizations apply for legislative grants, bonds or funding from the Alaska Energy Authority.

AHFC has a $250 million revolving loan program specifically for state and municipal buildings to invest in energy retrofits. A portion of the energy cost savings are used to repay the loans.

Before now, little was known about the energy use of public facilities statewide. Understanding the performance of these buildings is the first step toward improving it. This research lays the groundwork for future policy decisions, changes in building design and education for facility operators and owners.

The public building audit project was led by AHFC and supported by federal stimulus funds. It included more than 40 auditors and engineers statewide. The recently published white paper on the findings was pulled together by the project leads, with Richard S. Armstrong as lead author and editor. Other contributors to the white paper were Alaska Energy Engineering LLC, Central Alaska Engineering Company, Nortech Engineering Inc., Renewable Energy Alaska Project and the Cold Climate Housing Research Center.

The report is available at: http://cchrc.org/docs/reports/Energy_Use_PublicFacilities.pdf.

Adding glycol to your hydronic heating system is one way to boost the frost protection of your heating system, but first consider if it’s a good match for your system.

Every winter, several days of sustained cold temperatures tend to produce their share of frozen pipes. In the long term, the best way to protect water pipes is by addressing the source of the problems rather than the symptoms. This means insulating and air sealing the walls, floor, foundation or other cold spots that are putting those pipes at risk in the first place. If necessary, consider rerouting water lines to ensure they stay in heated space.

When it comes to the hot water (hydronic) heating system, solutions may not present themselves as readily. In many instances the piping may be inaccessible such as in concrete slabs, or the freezing risk may be too great if a mechanical breakdown occurs. In such cases, bolstering a heating system’s frost protection with glycol may present the best option. Although glycol is quite effective at keeping pipes from freezing, its use does have some important considerations as it has properties that differ from those of water.

For residential heating systems, propylene glycol is most often used as it is non toxic and environmentally friendly. Even so, make sure the glycol is compatible with your particular system and that it contains the proper additives. Typically, an experienced plumber will perform an inspection and decide what changes your particular heating system may require to make it compatible with glycol. Water hardness, the presence of chlorine and other impurities, and the metals used in the system (such as aluminum), can alter the system requirements and the additives in the glycol.

In some cases, a system where glycol has been added may experience weepage. Simply put, this means that marginal areas such as weak solder joints, pipe threads and other fittings that didn’t leak before may experience some leakage with glycol in the system. If leaks occur, they will need to be addressed. Fluid treated with glycol will expand to a greater degree and your expansion tank may need to be upsized. Also, since glycol does not transfer heat as well as water, depending on the amount in the system, this may result in a noticeable loss of system efficiency and a corresponding increase in heating cost. Ideally, glycol should be tested every year or two to ensure that its performance hasn’t degraded. Test kits are available at plumbing stores, or a plumber can test the system as part of routine boiler maintenance. In a properly operating system, glycol can last 10 years or more.

Along with the considerations mentioned above, glycol is an investment and introducing it into a system carries significant expense. Consequently, not every home may see the benefit and many have done fine without it for years, however there are times where it is the best solution for freeze protecting a heating system. Because every case is unique, what matters most is an experienced plumber is there to judge, inspect, and if needed, add glycol to the system to ensure the best possible performance with the fewest complications.

How an air source heat pump works. Photo credit: U.S. Department of Energy.

Air source heat pumps (ASHP) are a heating appliance that act like a refrigerator in reverse.  Where a refrigerator removes heated air from its interior and transfers it to the room, an air source heat pump extracts heat from outside a house, and transfers it to a home’s interior. Using an ASHP in colder climates seems counterintuitive, but the truth is that “cold” outdoor air still contains heat, and an ASHP uses electricity to “step up” that heat to a temperature useful for space heating. Until recently, ASHPs have been used in areas that only experienced mild winters.  However, ongoing advances in technology have resulted in ASHPs that can be installed in colder climates.

Southeast Alaska is a promising candidate for ASHP heating appliances, because it has a milder climate than the rest of the state and access to affordable hydroelectric power. Because ASHPs take some heat from the outdoor air and require less electricity than electric baseboards, they have the potential to reduce heating costs for homeowners who previously heated with electric appliances.

However, there is still uncertainty about the performance of ASHPs in cold climates, and about the barriers to their adoption in Alaska.  CCHRC is planning to explore the opportunity of using ASHPs in Southeast Alaska in a new project: Southeast Alaska ASHP Technology Assessment.  We will conduct a literature review, interview installers, distributers, and ASHP owners, create an inventory of existing ASHPs in Alaska, and model their economic and heating impact.  If you are interested, look for the Technology Assessment on our website in early 2013!

Read CCHRC’s Ground Source Heat Pump assessment here.

The UAF Sustainable Village is a community for students who are passionate about the environment and reducing their carbon footprint. It is a collaboration between the UAF Office of Sustainability and the  Cold Climate Housing Research Center  to build and research energy efficient housing, renewable energy, and innovative heating and ventilation systems. Students at the Village make a commitment to sustainability through monitoring the systems, conserving energy and water, and helping develop additions like a greenhouse or community center.

On Wednesday we will celebrate the opening of the Village with a ribbon cutting on-site and words by CCHRC President Jack Hebert, UAF Chancellor Brian Rogers, student workers and student residents.

For more info contact Molly Rettig, Communications Coordinator, at molly at cchrc.org.

Wednesday October 3, 2012 at 12 p.m.

11:30—Press invited to tour the interior of a student home

12:00—Ribbon cutting & brief words by Chancellor Brian Rogers & Jack Hebert

12:15—Move to CCHRC for brief ceremony—student posters on display

12:30—CCHRC President/CEO Jack Hebert welcoming

12:40—Words from student on design/construction team – Skye Sturm

12:50—Words from student resident

1:00—Time for interviews

1:15-1:30—Optional public tour of a student home

The homes are up, the students are moved in, and the heat is on! The construction site has been quickly transformed into homes with the arrival of students. Boxes of nails and piles of pipe fittings have been replaced with furniture, books, food, bikes and other everyday objects. The homes have a warm, homey feel on the inside and a very unique and eclectic yet natural look from the outside–a patchwork of bright colors and materials while surrounded by aspen, spruce, and natural habitat.

The Village is not just homes but also a research project, and science and innovation have been embedded throughout the site. Pressure transducers, flow meters, and other sensors are wired to data loggers and mini computers in each of the mechanical rooms to track how much fuel is being consumed and how much heat is being produced off the solar collectors. Thermistors in the ground will tell us whether heat is leaking through the foundation and whether the passive cooling system in the raft foundation is working. Students will help measure electricity, fuel use (of the pellet stove) and potentially many other aspects of the home’s performance.

Workers are doing finishing touches on deck railings, paint, and trim. But for the most part, the Village is looking complete. It’s exciting to see students starting a new chapter at the same time the Sustainable Village comes to life!