Tag Archives: energy efficiency

Policy Researchers Head Southeast to Meet with Building Communities

infrared image shows heat loss in the east end of the CCHRC Research Testing Facility

CCHRC is presenting one of the keynote addresses at the Alaska Municipal League (AML) Summer Legislative Meeting in Sitka this week. The AML, a statewide advocacy organization of 140 municipalities, meets each summer to discuss common issues and set legislative priorities at the state and federal levels.

CCHRC Senior Researcher for Energy Policy, Dr. John Davies, will present on energy efficiency as a resource for the sustainability of Alaskan communities. This will be a great opportunity to advance discussion of state energy efficiency policy recommendations that are part of work CCHRC is performing under a contract with the Alaska Energy Authority.  A long-term commitment to improving the energy efficiency of our buildings, appliances, and vehicles can reduce our need for energy by such large amounts that it should be considered as equivalent to large energy resources such as natural gas pipelines, hydroelectric dams, or coal-fired power plants.

Davies, along with Policy Research Director, Dr. Kathryn Dodge, will also visit Juneau and Ketchikan to meet with members of the building community about energy efficiency standards and the programs used to measure them. They will discuss and obtain feedback from builders, energy raters, and regulators on proposed policy recommendations, such as a statewide energy code, and present updates to a range of CCHRC programs.  One agenda item will be AkWarm, an AHFC computer program used to model energy use in homes and commercial buildings. AkWarm’s calculations are based on insulation levels, air tightness, and other thermal characteristics, and it is used to certify building for loans, rebates, and other purposes.

How do tankless hot water systems work and are they really more efficient?

Tankless hot water systems, also known as on-demand heaters, only produce hot water when you call for it—by turning on the sink, shower, or other appliance. They heat water instantly as it runs through a pipe and deliver it to your point of use, so you don’t have to store hot water in a tank and heat it all day. These on-demand heaters can be powered with propane, natural gas, or electricity.

You can save energy with this kind of system because you’re not paying to heat water when it’s not being used and you eliminate stand-by heat losses. Another benefit is that you never run out of hot water, unlike a tank system.

But a tankless system is prone to control and pressure issues. One problem is that on-demand heaters can produce bursts of cold water. For instance, if you finish taking a hot shower and turn off the water, the heater will shut off but the water in the pipes will remain warm (because they’re insulated). Yet the water inside the heater will cool off. So the next bather thinks the water is hot, jumps in, and soon gets a blast of cold water making its way through the pipes.

Another limitation of tankless heaters is that they can only heat a certain amount of water per minute. So if the washing machine is turned on during a shower, the hot water is split between the two uses, reducing water pressure all around. The good news? Both of these problems can be solved by adding a couple accessories to your system.

You can prevent cold bursts of water by adding a small, 2- to 10-gallon electric water heater (like a mini water tank) in between the tankless water heater and the point of use. This creates a buffer between sections of chilly water and your showerhead. The heater and installation will cost about $450.

The pressure issue can be fixed by adding a large pump to the system that can push enough water through the heater to accommodate multiple hot-water users at once. Adding the pump will cost about $650.

These add-ons drive up the price of a tankless system from around $300 (for the low end) to more than $1,000. Meanwhile, a hot water tank costs between $200 and $900. If you can live with idiosyncrasies like variable temperature and pressure, and don’t want the add-ons, then the tankless system will pay off in just a few years (thanks to energy savings). If you desire a system that is free of idiosyncrasies, the payback period will be much longer.

Which energy efficiency investments are best for my house?

foam insulation on the wall of CCHRC's Mobile Test Lab

That’s what an energy model will tell you.

How much insulation to use is one of the most common questions in the construction industry–among both contractors and homeowners. A steady increase in energy prices, along with growing material costs, makes it important to find the sweet spot between energy efficiency and affordability.

The Alaska Housing Finance Corporation provides standards, called Building Energy Efficiency Standards, or BEES, for different regions of Alaska to help guide these decisions. Home builders using AHFC mortgage loans must comply with these standards, but they also provide a good reference for anyone building in Alaska.

An energy model will tell you if you meet these standards. It’s a computer modeling program that runs a series of heat-loss and performance calculations for every single component of your house. You plug in the dimensions and construction details of all the exterior walls, roof, windows, foundation and floor, along with info about your heating and electrical systems, and you end up with a model of your home’s performance. The program also factors in climate data. You can change insulation values, construction types, heating appliances, and fuel prices to test a variety of conditions.

The best time to do the modeling is before you build, as it gives you the most flexibility to make changes. The best approach is to hire a state-certified energy rater to plug your house plans into the program, which should run between $350-$700 (but probably toward the lower end). You are required to get an energy rating anyway if you are using an AHFC funded mortgage loan to make sure you meet their standards. If you want to try energy modeling yourself, you can download a public copy of the AK Warm modeling program here (the one used in the state of Alaska).

Energy modeling is a powerful tool that can provide long-term savings and peace of mind with minimal up-front investment. Remember, though, that occupant behavior and awareness will also have a great impact on your home’s performance. A house bursting at the seams with teenagers will perform differently than the same one occupied by a retired couple.

Electronically Commutated Motors: are ECMs worth it?

There seem to be many ways to save energy in home heaters and air handlers. Recently I’ve been hearing about “ECM” motors in these appliances. What are they are and are they worth any extra expense?

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 amount of electricity needed to run your refrigerator.

One of the ways of accomplishing energy use reduction is by using electronically commutated motors (ECM). The construction of these ECMs allows the motor to run at different speeds, depending on the demand from the appliance. This type of motor has been in use in the US since 1985 and uses as much as 67% less power than that used by standard motors (PSC). That’s because sensors in the motor determine the need of the system and provide just the amount of energy needed. ECM motors are also quieter and cooler than standard motors.

A simple system that uses ECMs these days is a home hot water distribution system such as radiant-heat floors. The ECM runs the pump which distributes the hot water to heat your rooms. 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 run most efficiently, your 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 current furnace, HRV or other appliance with an ECM motor, it is generally more cost-efficient in the long run t 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.