Category Archives: Ask A Builder

The “Ask a Builder” series is dedicated to answering some of the many questions Alaska residents have about building, energy and the many other aspects of home life. Here you’ll find responses from CCHRC experts to commonly asked questions in Fairbanks, Alaska and beyond.

How does user behavior make a difference in my home’s efficiency?

Many people focus on the building envelope – the amount of insulation in the roof, the R-value of the walls, how many panes the windows have. Others think first of appliances – is the refrigerator certified as an ENERGY STAR appliance? What is the efficiency of the boiler? Does the hot water heater have a high energy factor? Are the lights incandescent bulbs, LEDs or CFLs?

Certainly all of these things have a role in making buildings energy efficient. However, there is an even more important factor that is often overlooked–the behavior of occupants. An oft-repeated saying in the building industry is “There is no such thing as a zero-energy home, just zero-energy homeowners.” Efficient buildings can’t reach their full potential if residents have energy-intensive habits. On the other hand, inefficient buildings can see large performance improvements just by changes in residents’ habits.

There are two main parts to energy efficient behavior: the types of appliances you buy and the way you use them. For example, do you own a large-screen plasma TV or a modest one? Both your consumer decisions and pattern of use play into your personal energy efficiency. For example, if you buy a 15-watt CFL floodlight and keep it on all the time, you may still actually use less than a 75-watt lamp that you turn off when not in use.
When it comes to your habits, remember what your mom and teachers probably used to tell you: Turn off lights when leaving a room; don’t leave the faucet running when you brush your teeth; take shorter showers; and put on a sweater instead of turning up the thermostat.

Changing habits can be difficult or uncomfortable, however, so there are also other options.

Many behavior elements can be addressed with technology:
· If you constantly forget to turn out the lights, or find yourself leaving on an outdoor light for hours while waiting for a spouse to come home at night, consider installing lighting controls. Motion sensors that can turn on and off lights are available for as little as $30 at home improvement stores.

· Programmable thermostats can be used to turn down the set temperature automatically while residents are away at work or asleep, and turn up the set temperature when residents are at home and awake. They can be programmed in 5 minutes – and offer savings on heating bills throughout the winter with no extra work.

· Do you have a number of devices plugged into the wall (phone chargers, TV, computer, etc.)? These devices draw a small baseline amount of current, called a phantom electrical load, as long as they are plugged in – even when they are turned off. Remembering to unplug everything can be difficult, but there are solutions. Plugging everything into a power strip means you only need to turn off one switch. Also, a smart power strip will shut off the current to peripheral devices such as a monitor and speakers when a central device, like a computer, is turned off.

· Do you have an electronic calendar on your phone or attached to your email? Use it to add automatic reminders for maintenance tasks, such as the yearly check-up on your heating appliance, or changing filters on a forced air distribution system. Remembering basic maintenance tasks improves the efficiency of equipment and prevents breakdowns.

· If you need to replace an appliance anyway, consider purchasing an Energy Star-rated one.

How else can you make your home more energy efficient? Go to www.cchrc.org or the website or Golden Valley Electric Association (http://www.gvea.com/resources/save) for more ideas.

Other resources on saving energy:
http://www.akenergyefficiency.org/
http://www.uaf.edu/ces/
http://www.energyhog.org/

What is a ground source heat pump?

A heat pump harvests energy from the ground to use for space heating for your home.

A ground source heat pump (GSHP) is a space heating appliance that uses electricity to convert geothermal heat to a temperature that can be used for indoor heating. They are common in the Lower 48 and quite popular in Europe. There are also several GSHP systems in Alaska, including commercial systems at the Juneau Airport, Weller Elementary School in Fairbanks, and the Alaska SeaLife Center in Seward. Fairbanks has more than 10 residential systems as well.

In the winter, ground source heat pumps work like refrigerators in reverse. Instead of taking heat from the inside of the refrigerator and rejecting it outside, a GSHP gathers heat from the ground, steps it up to a higher temperature using a compressor, and then “rejects” it inside a house. In the summer, some GSHPs can run in reverse mode to provide air conditioning – taking heat from a house and rejecting it to the ground. The main “fuel” for a GSHP is geothermal energy, but it uses electricity to run the compressor. Since the electricity is only acting to boost the geothermal heat (which is free), heat pumps are more efficient than electric heating appliances.

A GSHP consists of 3 parts: the ground loop, the heat pump and the distribution system. The ground loop gathers heat from the ground. It consists of loops of pipes buried in horizontal troughs or vertical boreholes. A pump moves a fluid through the pipes. As the fluid travels, it is warmed up by geothermal heat from the soil and returns to the heat pump with a higher temperature than when it left. Back at the heat pump, the fluid from the ground loop passes its heat to a refrigerant, causing it to evaporate into a gas. The refrigerant fluid then passes through a compressor and its heat can be “stepped up” before it transfers the heat to air or water for the distribution system. Heat pumps can work with a forced air distribution system or a radiant hydronic distribution system, however they generally are not capable of producing hot enough water for baseboard hydronic systems.

Ground source heat pumps are considered a partially renewable technology, because the heat they take from the ground comes from solar and geothermal sources. They are entirely renewable if the electricity they use comes from a renewable source, such as solar or wind. Heat pumps are also very safe to operate, because there is no combustion. They can, however, be expensive to install because you have to excavate land or drill to establish the ground loop. Talk to an installer if you think a GSHP might be right for you.

For more information on ground source heat pumps, see a report by the Cold Climate Housing Research Center and the Alaska Center for Energy and Power: http://cchrc.org/docs/reports/Ground-Source-Heat-Pumps-in-Cold-Climates.pdf. It covers the performance, cost and payback of GSHPs in various regions of Alaska.

Vapor Barriers & House Wraps: Where and Why

House wraps, such as Tyvek, are permeable enough to allow water vapor through but will stop bulk water like rain.

Vapor barriers and house wraps are a critical part of controlling moisture and air flow in and around your home. Working in conjunction with your walls, floor, and roof, the right type and application of these products will help you to conserve energy, prevent mold growth, and maintain the structural integrity of your home. Not using these products or using one incorrectly can wreak havoc.

 

Vapor Barriers
A vapor barrier, also known as a vapor diffusion retarder, is a layer of material designed to slow or nearly block the movement of water vapor. How much a vapor barrier impedes the movement of water is referred to as its permeability rating or, for short, “perm” rating. So it’s a bit misleading to use the term vapor barrier because many materials in this category do allow some moisture through. 6 mil thick plastic sheeting is a typical vapor barrier material prescribed by codes in extreme cold climates, as it’s perm rating is extremely low.

All homes generate moisture indoors. Cooking, bathing, breathing – all these activities create water vapor. Ventilation, which is essential to exchange moisture-laden air with clean dry air, helps to reduce the quantity of moisture in your home, but not enough to eliminate the need for a vapor barrier. Without a barrier, moisture can penetrate your walls and roof spaces.

Approximately 98 percent of water vapor in a home travels by air, but the remainder moves by diffusion – through solid materials such as the studs in your walls. When these materials become cold in winter, condensation forms and can trigger mold growth and other problems. The extreme air pressure and temperatures differences that occur in Fairbanks in winter exacerbate condensation problems. And, in the case of modern construction, tight building envelopes can serve to concentrate moisture problems in the absence of adequate ventilation.

House Wraps
House wraps, on the other hand, are designed to be permeable enough to allow water vapor to pass through them, but will stop bulk water like rain from passing through – sort of like Gortex in clothing. In addition, house wraps can help minimize the movement of air in and out of the exterior walls. Losing air from a house in an uncontrolled manner means that you are losing heat. This loss amounts to extra fuel costs and can become a burden on your budget.

To effectively repel water and reduce airflow, house wraps must be detailed correctly and applied using the manufacturer’s recommended methods and adhesives. All those protrusions through your walls such as vents, electrical connections, and architectural features must be carefully accounted for. The right types of house wraps can perform an important job in windy places by stemming significant heat loss.
Now comes the tricky part: some house wraps can also serve as vapor barriers and vice versa. Placement and permeability is also a fairly complicated issue. There may be certain cases when house wraps are not necessary, but when used are almost always placed on exterior of a house and over its sheathing.

More
The placement and permeability of vapor barriers and house wraps are addressed by building codes, but vary by region. Vapor barriers are required in Fairbanks. This article only touches on the details required to choose and install vapor barriers and house wraps. You can find resources at the CCHRC and the University of Alaska Fairbanks Cooperative Extension Service to help you make the right decisions. Doing your research up front can save a lot of problems later on.

How does a rainwater catchment system work and can I install one myself?

A simple do-it-yourself rainwater catchment system.

Installing a rain barrel to collect rainwater for non- potable uses is an easy way to help the environment and save money. Water collection systems can be as simple as a rain gutter directed into a barrel or as sophisticated as a buried tank supplied by multiple sources with filtration and pump systems. The easiest way to collect rainwater is to catch it as it drops from your roof and eaves. Of course, this works best if your home has large roofs fitted with gutters, but even a small roof can collect significant amounts of rain.

For every square foot of roof, you can collect a little more than a half-gallon of water per inch of rainfall. Fairbanks has an average of 10 inches of rainfall a year (some years much more, others much less). This means a small cabin in Fairbanks with a 1,000-square-foot roof can collect about 5,000 gallons of water per year–more if you collect snowmelt in the spring.

One thing you need is a tank. Storage tanks can be fiberglass, wood, steel, concrete, plastic, or another material, though plastic tanks are by far the most prevalent in Alaska. If the system will store water during the cold seasons, then outdoor tanks and lines need to be insulated to protect from freezing. Buried tanks should be at least four feet below-grade and are often protected by a top layer of insulation to prevent freezing.

You can often find small above-ground storage vessels at feed stores, or companies that deal in fuel storage, which sell everything from 15 gallon-60 gallon plastic barrels, some with spigots and some without. You may be able to purchase a much larger used tank from local excavation companies (the professionals who install domestic water holding tanks and septic systems) as they replace underground storage systems from time to time. Large new tanks can be found at plumbing stores, excavation companies, or local tank manufacturers.

A basic cistern system involves a series of gutters and downspouts that converge at a centralized collection point that in turn leads into the tank. If the tank is above ground, it may be beneficial if it is fitted with a drain valve and an overflow diverter. Provided the tank is elevated above the demand source, you can use a gravity-fed system to move water. If the tank has access from above, you may be able to move water with a submersible pump attached to a hose. The pump will provide more pressure and a consistent flow rate. Over time, the tank will fill with sediment, which will require cleaning periodically. Also, it’s a good idea to empty and clean the tank each year. This will help control algae growth, but also prevent damage due to freezing in winter. Be sure you support the tank adequately – just one gallon of water weighs around 8 pounds.

In general, the natural process by which rainwater is formed causes it to run slightly higher in acidity. In addition, the characteristics of your particular rainwater can be affected by sulfur and other pollutants in the air (if present), your roofing material, and any debris that may collect in the catchment system such as leaves, pollen, and bird droppings, for example. Downspouts, gutters, or the tank’s opening can be fitted with screens to keep large debris out of the system. More advanced systems include a trap to minimize unwanted matter from getting into your main tank. A trap is basically a smaller tank containing baffles. Water enters this smaller tank first and filters out sediment and other materials. You may want a system for diverting water from the collection system until a good rain has had chance to wash your roof of heavy pollen or other accumulations.

Consider what your roof is made of and ask the manufacturer to make sure your roofing materials are not toxic. It’s possible that old roofs may use asbestos shingles or other toxic materials.

If you’re considering a permanent catchment water distribution system, the acidity of the rainwater may need to be adjusted to reduce the long-term corrosive effects of the water on metal plumbing components.

If you are looking into building an advanced water catchment system, consider going just a few steps farther. Fitted with additional filters and plumbing, a cistern can provide grey water for indoor use and in some cases, drinking water.

For information on designing a system, check these resources:
Rain Barrel Construction by Cold Climate Housing Research Center, GW Scientific, City of Fairbanks, and Fairbanks Soil & Water Conservation District: http://cchrc.org/docs/green_inf/Rain_Barrel.pdf
Water Cistern Construction for Small Houses by UAF Cooperative Extensive Service: http://www.uaf.edu/files/ces/publications-db/catalog/eeh/HCM-01557.pdf
Information on Best Management Practices for rainwater catchment in Alaska: http://cchrc.org/docs/best_practices/BMPRWcatchment.pdf
Other ways to reduce rainwater and pollutant runoff on our website at http://cchrc.org/green-infrastructure.

How do I know if my boiler (or furnace) is the correct size for my house?

If you are thinking about purchasing a new boiler (or any other heating appliance) in the near future, make sure that you get one that is the optimal size for your house. Correctly sized boilers operate more efficiently and are able to keep your house at a comfortable temperature. A boiler that is too small will not be able to produce enough heat in the winter months, and a boiler that is too large will cycle on and off, wasting fuel, just like a car driving in stop-and-go traffic. Here are 3 ways to know if your current boiler is the correct size:

1) The rule-of-thumb: On the coldest day of the year, your boiler should run pretty much non-stop to keep the set temperature. Think of it as a car driving on the highway, getting a high miles-per-gallon since it doesn’t have to start and stop. If it does run non-stop, but your house does not stay warm, then the boiler is undersized. On the other hand, if you find your boiler cycling on and off during January’s coldest week, then you should consider getting a smaller boiler.

2) The calculations method: To determine what size of a heating appliance you will need, in addition to finding out information about what other energy upgrades you can make to your house, consider signing up for an energy rating. An energy rater will look at your entire house, measuring the air leakage rate with depressurization from doors and windows, checking insulation levels, assessing your heating system and checking for drafts. They will input this information into AKWarm, software maintained by the Alaska Housing Finance Corporation that calculates energy ratings. In a few weeks, you will receive the rating in the mail. It includes ways to improve the rating and other information on your house, such as the heating needs. An energy rating typically costs between $425-$550, but this will be rebated if you participate in the Home Energy Rebate Program (though you will likely face a waitlist for the rating). Visit the Alaska Housing Finance Corporation website for information on the rebate program and signing up for a rating: www.akrebate.com.

3) Do-it-yourself: The rating software AKWarm is available for free online. If you are computer-savvy and have a few hours to gather information on your house, you can use AKWarm to calculate your own unofficial energy rating. The software is available for download here: www.analysisnorth.com/AKWarm/AKWarm2download.html.

Should you insulate your basement or crawl space?

The foam board in this basement is in the process of being air sealed with tape at the joints and corners.

Concrete basements in many older homes are inadequately insulated by today’s standards (or not insulated at all). For new construction, both state and local building codes require a minimum R-value of 15 for below-grade walls (walls buried in soil).

This makes good sense as the soils in our region are relatively cold; even below the frost line, soil temperature may only reach a high of 36°F.

This means that in a poorly insulated basement, significant heat losses can occur year round. Basement walls that are well sealed and insulated, on the other hand, can save money and make yourhome more comfortable.

In older homes, it is often more practical to insulate the basement from the inside. If there are any problems with water penetration, make sure you fix them first or any work you do on the inside will be compromised.

If gutters and good site drainage don’t solve a water problem, then unfortunately excavating the exterior and applying a coat of waterproofing and resolving drainage issues may be necessary.

Rigid foam board or high-density spray-applied foam insulation make good choices for basement walls. Both products are resistant to air flow and can tolerate occasional exposure to small amounts of moisture. Depending on the type of foam, it will take between 3 and 4 inches to produce the minimum R-value of 15. Remember that the concrete behind the insulation is cold and will attract condensation if it is exposed to inside air.

If you use rigid foam board, then the joints should be tight, taped and also staggered if you are using several layers.

Be aware that building codes are strict regarding exposed foam in living spaces, and almost all foam insulations will have to be protected with some type of fire-proofing.

Once the foam is in place, then wood framing or furring can be used to run wiring and plumbing, and to provide an attachment for Sheetrock (which is a fire protection). Often, using a plastic vapor retarder is not advised if you will be insulating the basement walls with foam board. If properly sealed, the foam provides a good air barrier, and a layer of plastic sheeting will only reduce the wall’s ability to dry out, should moisture ever make its way in.

Basement walls that are well sealed and insulated can result in big energy savings and increased comfort. But because this area of your home will become much tighter, you may need to consider some form of mechanical ventilation to insure good air quality and humidity control.

What is a combined/integrated heating system?

Many homeowners use the same appliance to heat both their house and their domestic hot water. These multipurpose appliances are called combined or integrated systems.

 

Hot water for space heating goes into a hydronic distribution system or to coils for forced air distribution, while domestic hot water goes to a storage tank or directly to the faucet. Combined systems work with several types of appliances, including boilers, ground source heat pumps or solar thermal systems.

 

Combined systems offer several advantages over distinct systems. Since an integrated system provides both domestic hot water and space heating, you have fewer appliances to maintain. During the heating season, it’s more efficient to have a single appliance providing both hot water and heating because you have fewer on-off cycles. It also saves space.

 

On the downside, combined systems can be less efficient when the heating appliance only fires occasionally—in summertime, for example. In addition, it’s tough to measure the efficiency of combined systems because the rating on the appliance (known as the AFUE) only applies to space heating, not domestic hot water. A heating contractor or someone who owns the same appliance can give you a better idea of the actual efficiency.

 

There are two types of combined systems—storage tank and tankless. Storage tank systems are most popular. In this setup, the appliance simply sees the hot water tank as an additional zone, but one that is separated from the space heating system to avoid contamination of the drinking water. When the domestic hot water tank calls for heat, the appliance sends heat to that zone. Having a storage tank forces the appliance to fire only a few times a day to provide hot water. This design is more efficient than a tankless coil system because the appliance doesn’t have to fire as often, which is an energy-intensive process. Also, since there is no burner on the storage tank you can add extra insulation to the tank to save energy.

 

A tankless coil system has an extra heat exchanger that fits into the appliance. Water is heated when it flows through the heat exchanger. Tankless coil systems are most efficient when the appliance is already being used for space heating. During summer months, however, the on-off cycling that occurs every time domestic hot water is needed can waste energy. To avoid this, some homes use a tankless coil system during the winter and a separate domestic hot water system during the summer.

 

How can I maximize the efficiency of my refrigerator?

Refrigerators are often overlooked in the dialogue of energy efficiency. Typically, a new refrigerator with automatic defrost and a top-mounted freezer uses about half the energy of a 1990 version. So if your refrigerator is old and needs repairs, or is close to the end of its expected life, which could be around 15 years, then it makes good sense to replace it.

A new refrigerator with automatic defrost and a top-mounted freezer uses about half the energy of a 1990 version.

You can also enhance the efficiency of your fridge through proper maintenance. Seals can become brittle or lose their compressive memory, which can cause small gaps. As a rule of thumb, you shouldn’t be able to take a piece of paper and slide it between the seal. Another way to test the seal is to stick a flashlight inside the fridge. If you turn off the lights in the room and can still see light coming out of the fridge, then it’s probably time to replace the seals.

 

The refrigerator compartment should be between 36F and 38F and the freezer should be between 0F and 5F. You can’t always trust the dial in the fridge, so if you really want to be sure, put a thermometer inside and use the dial setting as a point of reference to make sure everything is working as it should. You may also want to clean the condenser coils, which are located at the back or bottom of the fridge. They can collect dust and force the fridge to work harder to do its job.

The location of your fridge is also important. If it’s sitting in the sun, next to the stove, or in any other warm spot, it will use more energy trying to stay cold. A fridge in a cold space will work the opposite way and save energy.

When you’re preparing food to go into the fridge, let it cool down fully before storing it away. Remember, a refrigerator is a temperature-regulating appliance. Hot food will raise the temperature inside the compartment and the fridge has to work harder to bring that temperature down to the level it is set for.

If you’re considering buying a new fridge, top and bottom units tend to be more efficient than side-by-side units. However, the bottom line when buying a fridge, or any appliance, is the yellow Energy Star tag. Energy Star information will tell you kilowatt hours per year for your model, which you can compare with other models.

Should I consider replacing my heating system?

If you’re thinking about replacing your heating system, here are some questions to ask yourself.  A “yes” to any of them may warrant a call to an energy rater or heating contractor.

Have you recently upgraded the thermal envelope of your house?

The thermal envelope of your house is everything that separates the living space from the outside, including walls, doors, windows, insulation and the roof. If you’ve been sealing leaks, eliminating drafts, replacing old windows with double-pane or triple-pane models, or adding insulation, you’ve been making your home more energy efficient.

With thermal envelope upgrades, the home will lose less heat in the winter and therefore the heating appliance won’t need to provide as much. This means your heating appliance is probably oversized and it may be time to replace it with a properly sized one that will operate more efficiently.

oil-fired space heater

Is your current heating appliance more than 20 years old?

Technology marches on. Appliances made today are far more efficient than older models. Not only do they use less fuel, they are also safer and come with more advanced controls to improve efficiency. Also, the methods to size a heating system are better and can be tailored to individual homes.

Is your house uncomfortable?

Do you have rooms that are always too hot or too cold? This can be the result of air leaks, inadequate insulation, an improperly sized heating appliance, or lack of zoning in your heating system. Start with a call to an energy rater to find out which improvements you can make to solve this problem. If you need to add insulation or seal leaks, take care of that before upgrading your heating system so that the heating system will be sized properly for your home.

Who do you call?

Energy raters will look at your entire house, measuring doors and windows, checking insulation levels, assessing your heating system and checking for drafts and leaks. The rater will input the data into AKWarm, software maintained by the Alaska Housing Finance Corporation that calculates energy ratings. The rating describes how efficient your house is and suggests ways to improve the rating, which may or may not include the heating system. The rating will help prioritize upgrades, show the energy benefits of each one, and may qualify you for the Alaska Home Energy Rebates Program.

Heating contractors will focus specifically on your heating system, evaluating its current efficiency and whether it is sized properly. A contractor can sometimes test for the efficiency of the distribution system (depending on the type). The contractor will provide you with information on improving your current system and purchasing new appliances.

Is my heating system the correct size for my house?

A hot fire burns more efficiently than a smoldering fire.

Just like skiers ride best with the right sized boots, your house needs a properly sized heating system to perform at its highest efficiency. Oversized heating systems are inefficient and cost more, both upfront and in ongoing maintenance, than a heating system that fits your home.

Heating appliances are sized by the amount of heat they can provide in one hour. This heating capacity is measured in BTUs per hour (one BTU is about the amount of heat energy produced by burning one match).

The heating capacity of your system should match the peak hourly demand of your house. Peak hourly demand is the maximum heat required by a house in one hour on the coldest day of the year. For a rough estimate, a well-insulated, two-story house in Fairbanks might require 60,000 BTUs per hour on the coldest day of the year, so a heating appliance should be rated to produce that much heat.

A properly sized heating system will run continuously on the coldest day in order to keep the home at its set temperature. This means the system is running at its steady-state efficiency, the stride it hits after warming up. Steady-state efficiency is like the miles-per-gallon your car gets cruising on the highway as opposed to riding in stop-and-go traffic.

Oversized systems, on the other hand, tend to cycle on, produce lots of heat, and turn off. The cycling on and off wastes fuel (as the appliance repeatedly ramps up and cools down) and causes wear and tear on the mechanical system (which ultimately requires more maintenance).

Wood- and coal-fired devices can also be oversized. When a wood stove is too large, residents tend to burn fires at a low smolder to prevent overheating the house, which is not only less efficient but also emits more particulates than a hot fire.

Domestic hot water systems should also be properly sized. For example, storage water systems are sized by their First Hour Rating (FHR), the amount of hot water in gallons the heater can supply per hour, starting with a full tank of hot water. The FHR (determined by the size of the water tank, source of heat, and size of the burner or element) should be within a few gallons of a building’s peak hourly hot water demand. F

or example, a household of three who routinely shower at night while running a dishwasher may have a peak hourly demand of about 45 gallons. So the house would need a domestic hot water heater with a First Hour Rating of 40-50 gallons. For tankless water system, the size depends on water usage, fuel input and the temperature of the incoming water.

The size of a heating system is directly related to the efficiency of your home. So if you make any building envelope upgrades to your home, you’ll require a smaller heating system—a good reason to make upgrades before replacing your heating appliance.

Sizing your system

Rule-of-thumb methods should not be used to size a heating system because today, sophisticated computer software exists that can help contractors with this task. Contractors in Alaska should use one of two methods to determine the proper size of your heating system:

–ACCA Manual J by The Air Conditioning Contractors of America

–AKWarm software, maintained by the Alaska Housing Finance Corporation, provides sizing methods for heating systems.

Don’t be afraid to ask your contractor how he will size your heating system, and ask to see the calculation.  Remember: a properly sized heating system will save you money.

You can calculate your hot water peak hourly demand for a storage water heater at the U.S. Department of Energy website on hot water heaters: http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12990