Breaks in the Thermal Boundary

Our homes are involved in a climate struggle 365 days a year. It’s an on-going battle every home fights. The outdoor climate against the indoor climate determines how comfortable we are and how high our power bill becomes.

The larger the battle, especially if the indoor climate is losing, determines how open we are about learning how to be energy efficient at home.

The conditioned air inside our home makes up the indoor climate. We are the ones, with the help of a good thermostat,  that determine the temperature of the indoor air.

The indoor air is conditioned by:

1. Heating and cooling systems,
2. Exhaust fans,
3. Open windows,
4. Taking showers,
5. Leaving lights on,
6. Buying a new flat screen, etc.

The outdoor air is conditioned by:

1. Mother nature,
2. Sun flares,
3. The gravity of the moon,
4. Changing seasons,
5. Coal fired power plants, home location, etc.

Breaks in the Air Boundary

Some homes contain all conditioned space while others have a combination of conditioned and unconditioned space. Unconditioned space may include attics, crawlspaces, basements, and attached garages.

Some places, such as furnace and utility rooms are warmed by waste heat and are called unintentional conditioned spaces. They act as buffer zones between the indoor climate and outdoor climate zones. They help slow the transfer or loss of heat.

How to be more energy efficient at home is partly determined by how well the thermal boundary is defined. The conditioned space is identified by that space that is surrounded by the two barriers that make up the Thermal boundary.

1. The Air barrier

• The air barrier restricts the flow of air between the conditioned space and the unconditioned space.

2. The Insulation barrier

• The insulation barrier slows the transfer of heat between the conditioned space and the unconditioned space.

How the Thermal Boundary contributes to energy waste:

Completing the Envelope

Breaks in the air barrier and the insulation barrier result in energy waste. The hole the plumber drilled that was never air sealed and the missing insulation in the attic contribute to energy waste and higher energy bills.

The insulation in the attic that separates one area of unconditioned space from another area of unconditioned space is wasting energy. The insulation is simply in the wrong place.

The dog that ruins the back door weatherstripping has, in-effect, damaged the air barrier and is now contributing to energy waste.

It is a poorly defined and inadequate thermal boundary that contributes to energy waste and inefficiency.

The Role of the Energy Auditor:

It is the energy audit, whether by a professional or by the homeowner, that determines the cost-effectiveness of completing or adding to the thermal boundary. It is also the energy audit that confirms the thermal boundary is in the correct location.

Modern homes that have several dormers, bay windows, roof levels, irregular soffits, and knee walls, are likely to have a broken or misplaced thermal barrier.

Where's the Thermal Boundary

Factors that determine the thermal boundary’s location are:

• The building shells current insulation level.
• The effectiveness of existing air barriers.
• The structure of the home that will allow a continuous and unbroken thermal boundary.
• The determination of what is conditioned and unconditioned space.

The air barrier and the insulation barrier should be close together, even touching in most areas. Air flowing through and around insulation is one of the most common energy wasters, therefore, the two barriers should be joined, together, on the same plane.

The thermal barrier plays a huge role in your homes battle to separate the indoor climate from the outdoor climate. The two components of the thermal barrier, the air barrier and the insulation barrier, need to be located and installed correctly if your home is going to have a fighting chance to win the climate war.

How to be energy efficient at home has more to do with a good thermal barrier than with a new high-efficiency furnace or heat pump. Don’t spend $5,000 on a new heating system until you spend one quarter of that on your homes thermal barrier.

Thanks for stopping by Detect Energy, hope you will come back soon, but I won’t leave the light on for you…

The Energy Field Favors Solar

The cost of solar energy rivals electricity produced by much less environmentally friendly sources.

If you’re thinking about switching to solar energy, now’s the time. Prices have never been lower, and in some areas, PV systems can now produce electricity at a cost that’s competitive with — or even lower than — conventional electricity from coal, nuclear or natural gas.

That’s right — the day we’ve all been waiting for has finally arrived. The cost of solar energy rivals electricity produced by much less environmentally friendly sources. What’s more, the cost of solar power will continue to fall while the price of conventional fuels spirals upward.

40% in Two Years

The cost of a residential solar power system has dropped about 40 percent in just the last two years. As a result, the lifetime cost of solar electricity produced by these systems now competes with conventional electrical power plants. In places where electricity sells for a premium, it’s competitive even without subsidies.

In New Jersey, for instance, conventional electricity costs about 17 cents per kilowatt-hour (kwh). A residential solar power system can produce electricity at or slightly lower than that price, without any incentives.

Families in many major cities are paying 10 to 12 cents per kwh for conventional power, and soon, many in the Midwest will pay up to 15 cents/kwh for conventional power. Meanwhile, in the Midwest, the unsubsidized cost of solar power is about 13.7 cents/kwh, and a 30 percent federal tax credit drives that cost down to 9.6 cents/kwh.

Rebates Lower Installation Costs

Friendly Rebates

Rebates that are available from some utilities lower the price even more. In St. Louis, Ameren offers a $2 per watt rebate based on installed capacity. A 5 kilowatt system would receive a $10,000 rebate as soon as the system is up and running.

This incentive drives the cost of solar energy down even further — to 7.1 cents/kwh. That’s much cheaper than conventional power. In addition, the cost of solar electricity will remain the same for the life of the system — at least 30 years, maybe longer. This provides a tremendous hedge against inflation.

original article at,   motherearthnews.com 

Read more:   motherearthnews.com

Ride Share Efficiency

Car2go, one of a growing trend of car sharing options, has come to Berlin, placing 1000 Smart-for-Two cars around Germany’s capital, where registered users can pick up and drop off a car as they need one. With over 2000 pre-registrations, the launch is off to a good start.

Car2go is a subsidiary of Daimler, the company behind the brands Mercedes and Smart Car. In spite of the fact that Daimler represents German culture as well as any company can, the comments to the news about car2go in the German media delve into how strange the name car2go sounds in the German language.

German verbs tend to be very precise.

When I first arrived and was learning the language, it would always bring a smile to the face of anyone I would tell that I am “going” to America. “To go” in German, implies that one is walking. One can fly to America, but it is unlikely that one would “go” there.

Owning a Car is More Expensive

Similarly, the concept of describing “take away” items as “to go” sounds quite foreign to the German ear. So the pun is lost, and Germans are left wondering just how, exactly, can one have a car to walk?

Snickers aside, the car2go program offers people a flexible and simple car rental option intended to make car ownership in the city unnecessary. It cost 9.90 euros (US $13) to register. A car can be used for 29 euro-cents per minute — a rate that includes applicable taxes, insurance, fuel and parking costs, and the first 20 kilometers traveled. The rate drops to 9 euro-cents per minute if the car is parked. Alternatively, a one-hour car2go rental costs 12.90 euros and daily rental (24 hours) costs 39 euros.

Apple Phones Too!

The launch in Berlin also introduces a smart phone App, initially for use on Apple phones, that helps users find the nearest car2go.

Another world premier: the car2go Smarts are outfitted with hyper-miling monitors that will assess drivers’ braking, acceleration, and coasting to deliver a score in the form of one to three trees. While not yet available, Daimler has suggested the introduction of a program to offer drivers that score three trees some kind of rebate, in the form of free minutes for example.

Is Public Transport Threatened?

Cutting Down on Burning Fossil Fuel

Not at all. In fact, Daimler’s car2go cooperates with the public transport authorities of Berlin and the surrounding regions. In the words of the Berlin Transport company (BVG) Chairwoman Dr. Sigrid Nikutta:

Buses and subways are the backbone of the local public transport system. An intelligent link with supplementary services enables us to offer our customers the opportunity to choose and combine additional convenient options from the city’s various means of transport in line with their needs. Our goal here must be to set up a system that combines the entire product range in the form of a ticket or entry into a standardized information system.

This will make it possible for Berliners and their guests to move through the city on buses and trains, by bike, or with a taxi or electric vehicle as needed. In this sense, car2go is an important partner for us as we move to transform our mobility vision into reality.

Although commenters in the German media have also questioned the need for yet another 1000 cars parked in Berlin’s rare parking spaces, only paying for a car when you need one makes sense to us. If the car sharing concept leads to less individual car ownership, everyone wins.

Add Insulation to the Attic

Having a well-insulated home is not only a great way to live toward a greener ideal, but to also save yourself some money on heating and cooling bills. Heat is constantly in movement moving from a warmer to a cooler area, i.e. escaping from within your warm house to the cold outside.

This heat flow can be reduced through insulation giving your home a higher heat flow resistance also referred to as an R-value. The better your R-value, the more you save on bills and the more energy efficient your house is. This article presents what options you have when improving insulation, and looks at small to big changes.

Small Changes are Important

Just a few changes and improvements can make a difference to your home. For example, if you have wood framed windows, check their frames for damages and if need be fill in any gaps with wood filler. If you have aluminium windows then you can add draught excluders for better insulation.

Spray Foam Insulates and Air Seals

As a lot of heat escapes through windows, consider what window treatments you have. Wooden blinds or wooden shutters are good for insulation and fit in well with most home décors. But heat can also escape through door gaps. Bottom door brush draught excluders are good at preventing this, and are discrete, too. The door draught excluders made out of material are more fun to look at, but can get in the way a bit.

Bigger Changes Include the Attic

As heat rises, another “hotspot” for it to escape is through your roof. The traditional insulation methods for an attic are loose-fill and batt insulation. Before choosing one of these insulation types, the attic must first be air sealed, meaning using a tightly constructed box to cover fan housings on the attic side of a duct and covering openings such as dropped ceilings, soffits, and bulkheads with plywood and sealing them towards the attic side of the ceiling.

Loose-fill insulation is cheaper than batt, and if done right loose-fill can provide better coverage. If you have vermiculite insulation in your attic, there’s a danger of it containing asbestos. Do not disturb it and instead hire an insulation contractor to handle it. Loose fill is generally blown into the attic above the ceiling joists by an expert, while batts ,which are mineral wool fibre sheets, can be placed in a criss-cross pattern between the joists by yourself, if you feel up to it.

Wall Insulation for Older Homes

Don't Forget the Walls

Wall insulation differs between wood frame and solid brick frame walls. Wood frame wall insulation uses loose fill or sprayed foam, which is blown into the cavity of the wall via holes drilled into the drywall or siding. As a cavity of a solid brick wall is often 25 mm and therefore too small a fill to gain any insulation benefits, a professional must create a cavity. A new cavity wall is built on the interior side of the wall while board stock and new siding are applied to the exterior of the wall.

Basements Can be Tough to Insulate

Basement insulation is advantageous but also a bit controversial as there are many factors which influence this. The energy savings and cost savings are dependent on the local climate and the type of heating system you have. Once you’ve checked if insulating your basement is the right thing for you and your home, you can then decide between wall or ceiling insulation.

Wall insulation is easier and more common, and includes rigid insulation, like extruded polystyrene or rigid fibreglass being installed to the exterior of the walls. Ceiling insulation in an interior insulation, and can be costly due to the material being used.

Peddle Power Carpooling

You can reduce your energy usage by just reducing your electricity usage. For example, when an appliance is not in use unplug it. Always turn off the television and lights when you are not using them. This is an excellent way of saving yourself some money.

Carpooling

Think about using a carpool for work and other activities in order to reduce the amount of fuel you use. Carpooling with other neighborhood parents to transport children back and forth to school not only saves you time, it sames you money. If you love in close proximity to family members or friends, try to synchronize your shopping trips with them, and you can each take turns driving.

 Solar Power

Solar power can heat water for a low cost. Look into hot water systems that run by solar power. You could choose of having an indirect or direct circulation system. If you have been plagued by frozen or broken pipes in the past, an indirect one could be for you.

Solar Power Brings Communities Together

Incentives, Rebates & Tax Credits

Look for rebates at the local and federal levels for updating your home to renewable energy sources. Some utility companies also provide rebate opportunities for the installation of green technologies. You may also qualify for tax credits or deductions from your state or from the federal government. These credits and rebates can cut costs greatly when installing green technology in your dwelling.

Nothing is Greener than Passive Solar Power

Find out more about active and passive forms of solar power. Active power is the power stored for later use and passive doesn’t require pricey cells for storing power. If you use active power, you will need to install mechanical systems, solar panels and cells. While passive simply uses the sun in storing thermal energy in your walls in order to heat your house.

Support Green Products

Berkley Green Household Products

Help reduce the cost of green energy by increasing the demand for it. As a consumer, demand technology that is environmentally friendly. As demand and consumption of products made from environmentally green companies rises, the availability of these products will increase. This will also tell companies who aren’t engaging in environmentally safe practices that they need to change or they’ll lose you as a customer.

Brighten With Paint

One way to save money on lighting is to use paint for your walls that is lighter and brighter. If your walls are painted a dark color, you will have to use more light to brighten it up, which makes your home less energy-efficient. If you choose lighter colors instead, your home will naturally feel brighter, and save you money in energy expenses as well.

Bright Savings

Turn the lights off when not in use. Lighting your home at night is necessary, but turn them off if a room is not being used. Don’t forget to also turn off your porch and cabinet lighting when not in use. This will decrease energy consumption.

Personal Tankless Heater

Tankless For You?

Use an on-demand water heater to save energy. Traditional water heaters are always on and heating unused water, which is a tremendous waste of energy. A on-demand water heater will only heat your water when you need it, which saves a ton of money and energy.

Monitor Power Bills

Keep a record of your energy efficiency goals. Each month, check your utility bills to check your year-over-year progress with regard to saving energy. If you are more conscious of what your energy expenditures are, this could help to lower them. For instance, reducing your electricity or water usage will get you into the habit of turning off appliance and lights when not used.

Environmentally Green Lifestyle

Making use of green energy today could save you a lot of money, and it will also save the environment as well. Being environmentally friendly does not take an advanced degree or a scientific background. Use the tips presented here that fit your own situation, and incorporate them into your life. It’s easier than you think.

The subject of environmentally friendly energy is incredibly topical these days and that is why we have authorities whom are usually at the moment working on energy saving light bulbs. Should you have any sophisticated concerns on the LED bulb then these people are going to be thrilled to assist.

original article at Lexicon

Apartment Energy Audit

How do you improve the rental unit efficiency of apartments and other rental units when renters don’t own the property or appliances and landlords don’t see the benefits in their pocketbooks from improvement because they don’t pay the utility bills? It’s a much-debated conundrum that even has a name: the “split incentive” problem.

At first, improving the efficiency of rental properties seems like a straightforward idea. Apartment buildings present a huge opportunity for energy savings because of their high density, and tenants want to save energy because it lowers their utility bills.

But many of the techniques a homeowner can use to save energy—weatherization, window upgrades, or more efficient appliances—aren’t possible because the tenant doesn’t own the property. Landlords, on the other hand, don’t have an incentive to make the upgrades because they aren’t paying the electricity bill.

Split Incentives Solutions

A new report from MN2020, called Sensible Incentives: Enabling Energy Efficiency in Rental Housing, takes a closer look. The report focuses specifically on refrigerators in rental housing units, determining the amount of money and energy saved by swapping inefficient appliances for new, energy-efficient ones.

According to the study, “replacing the nearly 88,000 refrigerators over 10 years of age in Minnesota rental properties would save renters well over a staggering $3.7 million a year.” And that’s just one appliance!

Policy Solutions

Still Need Energy Efficiency Incentives

The report also suggests the following three policy solutions to improve efficiency in rental units:

1. Customized Conservation Improvement Programs for large rental property owners that provide rebates for the replacement of old, inefficient refrigerators

2. Mandated disclosure for apartment buildings’ public energy use so that people know how much they are going to pay in energy costs for a rental unit, similar to how water heaters and refrigerators give you an estimate of estimated annual energy usage already

3. A pilot on-bill financing program for appliance upgrades that serve rental housing— a tool that allows customers to pay for energy efficiency investments though their utility bills by spreading the cost for the improvements out over time and paying them back slowly as part of their utility bills.

The report is based on work by Fresh Energy and Humphrey Institute Capstone students Will Nissen and John Mitchell in 2011 (Nissen is now a policy fellow at MN2020).

Original article at fresh-energy.org

With Energy Efficiency

With high temps in the 80s over the past few weeks here in Virginia, there’s no question that Spring and Summer are on their way into the region. And with that, it means time to get outside and start working on the house for some energy efficiency cooling measures.

Cutting the grass, mulching, weed-pulling, repainting the mailbox, and cleaning your gutters are all on the high priority list.

But this year, add a few more to the list:

1.  Change your air filters.

2.  Plant deciduous trees near your AC unit, to cool the air that your unit uses.

3.  Check around your house for cracks and leaks (Can you see light through the crevice around your door? You might need some weather stripping).

4.  Check to make sure the insulation under your house hasn’t fallen out from the floor joists.

5.  Clean your ceiling fan blades, and make sure the air is blowing downwards when the fan is on.

6.  Change your light bulbs to CFL lights (Think about all the money you can save!).

7.  Open your foundation vents.

And here is our popular video on Summer Energy Savings Tips.

Posted by Stephen,  www.dom.com

If the video does not open for you, try this link,  http://www.youtube.com/watch?v=Z0EZ3nxXctg

About Dominion

Dominion is one of the nation’s largest producers and transporters of energy, with a portfolio of approximately 28,200 megawatts of generation, 11,000 miles of natural gas transmission, gathering and storage pipeline and 6,300 miles of electric transmission lines.

Dominion Has Power

Dominion operates the nation’s largest natural gas storage system with 947 billion cubic feet of storage capacity and serves retail energy customers in 15 states.

Dominion practices environmental stewardship and contributes more than $20 million annually to the environment, education, arts and culture, and health and human services, and energy efficiency.

Dominion’s strategy is to be a leading provider of electricity, natural gas and related services to customers in the energy-intensive Midwest, Mid-Atlantic and Northeast regions of the U.S., a potential market of 50 million homes and businesses where 40 percent of the nation’s energy is consumed.

AO Smith Heat Pump Water Heater

Now that pilot studies show that installed heat-pump water heaters are performing fairly well, it might be time to buy one.

Heat-pump water heaters are about twice as efficient as electric-resistance water heaters. They are also taller; this Voltex model from A.O. Smith is almost 7 feet tall.

The least expensive way to heat domestic hot water is with natural gas. Homes without access to natural gas usually choose an electric water heater, since electricity is generally cheaper than propane.

Although most electric water heaters use electric resistance elements to heat water, a more efficient method uses a heat pump — in other words, a device that heats the water using a compressor like the one found in a refrigerator or air conditioner. While a refrigerator transfers heat from the interior of the refrigerator to the room where the refrigerator is located — in effect, heating the room — a heat-pump water heater transfers heat from the room to a tank of water — in effect, cooling the room.

Heat-pump water heaters need backup elements

Compared to an electric-resistance water heater, the main benefit of a heat-pump water heater is energy efficiency. While the efficiency of electric resistance elements is 100% — all of the electrical energy sent to a resistance element is converted into heat — the efficiency of an air-source heat pump can be as high as 250%. The heat-pump isn’t making heat — it’s transferring heat from the air to the water. A heat pump is capable of transferring more energy than the energy required to run it.

The type of heat pump use for heat-pump water heaters can’t heat water as quickly as electric resistance elements, however. While the electric-resistance elements in a typical water heater can heat 20 gallons per hour, a heat pump can only manage about 8 gallons per hour (or even less, if the ambient air temperature is below 68°F).

To make up for this basic deficiency in heat-pump performance, heat-pump water heaters are equipped with electric resistance elements that are energized whenever the heat pump can’t keep up with the demand for hot water. This feature improves the performance of the unit but introduces an energy penalty.

GeoSpring Heat Pump Water Heater

Most heat-pump water heaters have controls that allow a homeowner to choose one of three modes of operation:

1.  Heat-pump-only mode (a mode that is energy-efficient, but that doesn’t allow long showers).

2.  Hybrid mode (heat-pump operation plus electric resistance backup).

3.  Electric-resistance-only mode (a mode that you could choose during cold weather, when you might not want the appliance to cool the space where it is located).

Heat-pump water heaters are clearly more efficient than electric resistance water heaters. Possible side benefits include dehumidification of the room where the unit is located, and space cooling (a side effect which is beneficial in hot weather but potentially problematic during the winter).

Measuring the efficiency of electric water heaters

Electric water heaters (both electric-resistance water heaters and heat-pump water heaters) are rated with an Energy Factor (EF) that is based on a standardized laboratory test procedure. The EF rating is the ratio of the energy delivered to the water divided by the energy used by the water heater. An EF test takes 24 hours; the testing standard specifies the volume and spacing of the hot water draws, as well as the temperature of the hot water and the ambient temperature of the room. An EF rating takes into account standby losses but not distribution (piping) losses.

A typical EF for a heat-pump water heater ranges from 2.0 to 2.5, while a typical EF for an electric-resistance water heater is 0.9. (The EF of an electric resistance water heater is always less than 1.0, due to standby losses through the tank insulation and at the pipe connections.)

While a unit’s EF must be measured in a laboratory, researchers can calculate a water heater’s coefficient of performance (COP) in any location where the unit is installed, as long as the proper monitoring equipment is in place. While the EF of an appliance is fixed, the COP of an installed water heater will vary, depending on the ambient temperature of the room where it is installed and the water use habits of the family using the water heater.

A heat-pump water heater with a COP of 1.8 is twice as efficient as an electric-resistance water heater with a COP of 0.9.

Factors that affect performance

Accelera Heat Pump Water Heater

A recent pilot study by researchers from Steven Winters Associates monitored the performance of 14 heat-pump water heaters installed in the basements of 14 homes in Massachusetts and Rhode Island. The study was sponsored by three electric utilities: National Grid, NSTAR, and Cape Light Compact. Robb Aldrich presented the results of the study on March 7, 2012 at the NESEA-sponsored Building Energy 12 conference in Boston.

The monitored water heaters included ten GE GeoSpring units, two A.O. Smith Voltex units, and two Stiebel Eltron Accelera 300 units. The water heaters were installed in older existing homes, not new high-performance homes.

The cost to operate a heat-pump water heater is hard to predict, because performance depends on the ambient temperatures of the room where it is located and the percentage of time that the electric resistance element is on.

The researchers identified the following factors that affect the performance and efficiency of heat-pump water heaters:

The higher the ambient temperature in the room where the unit is located, the better its performance and the better its energy efficiency. A unit that might perform at a COP of 2.35 at 68°F will only perform at a COP of 1.8 at 50°F.

The units installed in homes that used a lot of hot water (up to a point) had a higher COP than those installed in low-use homes. “If you don’t use much hot water, your COP is low due to the standby losses,” said Aldrich. “If you use more, the standby losses are smaller, so the COP is higher.”

Large volume draws of hot water cause the electric-resistance elements to kick in, thereby lowering the COP. “Concentrated draws of hot water make it hard for the heat pump to keep up,” said Aldrich. “A larger tank or a hotter tank might solve this problem.”

Energy use monitoring data

The measured performance of the 14 heat-pump water heaters enrolled in the study was fairly good. On average, the monitored COP was 1.9 — meaning that the units were more than twice as efficient as an electric-resistance water heater operating at a COP of 0.9.

The best-performing unit (located in a warm basement) had an average COP of 2.6, while the worst-performing unit (located in a small room in a very cold basement) had an average COP of only 1.0.

Where would I put a heat-pump water heater?

There are three places where you might put a heat-pump water heater:

1.  If you live in a warm climate and you have an attached garage, put it in the garage.

2.  If you don’t have an attached garage or you live in a cold climate, put it in the basement.

3.  If you don’t have an attached garage or a basement, put it in a utility room — as long as the utility room is big enough.

It’s important to note that these three locations aren’t equivalent, and the performance of the heat-pump water heater will vary depending on the conditions of the room where it is installed. Many homes don’t have a good place to put a heat-pump water heater.

Before you can install a heat-pump water heater, you need to be sure that you can fulfill all of these requirements:

Efficient Water Heating

You need a room that is big enough; most heat-pump water heater manufacturers advise that the room should measure at least 750 or 1,000 cubic feet, although at least one manufacturer allows its unit to be installed in a room measuring only 500 cubic feet. Remember, in a small room, performance will suffer.

Ideally, the room will stay above 50°F all year long; however, if the temperature dips lower occasionally, your water heater will still work, although its efficiency will drop.

The room’s ceiling must be high enough to accommodate the water heater. Heat-pump water heaters are taller than electric-resistance water heaters. These units range in height from 63 inches for the G.E. unit to 82 inches for the A.O. Smith unit. Check the manufacturer’s specs before placing your order.

The location must allow for the installation of a condensate drain. If a gravity drain (a floor drain) isn’t possible, you’ll need a condensate pump. Since a 120-volt condensate pump that is plugged into a GFCI receptacle will stop working every time the GFCI has a nuisance trip, you probably want to order a 240-volt condensate pump and have it hard-wired.

The proposed location must be roomy enough to allow for proper airflow around the unit and for proper maintenance of the filter, the condensate drain, and other parts.

The temperature of the room in which the unit is installed will drop when it is operating, by anywhere from 2 F° to 6 F° — and perhaps even more during heavy draws of hot water. The location should therefore be one where such temperature drops don’t lead to comfort problems.

The location must be far enough away from occupied areas (especially bedrooms) to prevent noise complaints. “The sound level is about 60 decibels,” said Aldrich. “That’s like a window air conditioner — louder than a refrigerator.”

According to most researchers, garage installations are usually the best. Garages are big, and it’s unlikely that there will be any complaints due to the unit’s cooling effect or noise. Of course, if you live in a climate that is cold enough to freeze pipes in your garage, you’ll have to find somewhere else to put it.

How much space heat do they steal?

How It Works, Accelera 300

Clearly, a heat-pump water heater scavenges heat from ambient air, thereby cooling the space where it is located. However, this is not always a problem.

It’s not a problem in a garage.

In a hot climate, even if the heat-pump water heater is located inside a home’s conditioned space, the unit’s cooling effect will be welcome for most of the year.

In a cold climate, a heat-pump water heater installed inside a home’s conditioned space will rob space heat, forcing the home’s furnace or boiler to work a little harder.

In the worst-case scenario, all of the heat scavenged by the water heater during the winter is robbed from a home’s conditioned space. However, if the unit is installed in a basement, it’s unlikely that the space heating system will need to supply all of the heat scavenged by the heat pump. After all, most basements aren’t heated directly; all they receive is indirect heat.

Assuming that the basement in not used as living space, some but not all of the heat scavenged by the water heater will come from the furnace, and the basement will stay a few degrees cooler than it would have been otherwise. For many homeowners, cooler basement temperatures aren’t a problem. The fact that there is a slightly higher delta-T between the first floor and the basement will have only a very small effect on the home’s heating load.

Quantifying these interactions is extremely tricky. “It’s a crazy thing to try to model,” said Robb Aldrich. “So what we have done is to try to bracket it. If the heat-pump water heater robs no heat from the space” — for example, if the unit is in a garage — “then all the measured electrical savings are really savings. On the other hand, the worst-case scenario would be if the heat-pump water heater operated in resistance-only mode for six months of the year.

That’s unlikely; it’s the worst-case scenario. What this means is that from the standpoint of energy consumption, a heat-pump water heater is almost always going to be better than just electric resistance, and often quite a bit better. Yes, the heat is coming from the space during the winter, but not every BTU that you take from the basement needs to be replaced by the heating system; that percentage will vary widely.”

Can the exhaust air be ducted outdoors?

At least one heat-pump water heater manufacturer (AirGenerate of Houston, Texas) allows the exhaust air from the heat pump to be ducted to the outdoors. The idea is that if your heat-pump water heater is making your utility room too cold, you might want to send the cold exhaust air somewhere else.

There’s only one problem with this approach. According to David Kresta, a project manager at the Northwest Energy Efficiency Alliance in Portland, Oregon, the temperature of the exhaust air coming off of a heat-pump water heater is in the range of 45°F to 60°F.

If you send all of that exhaust air out of the house, an equal volume of makeup air will enter the house from the outdoors. If the outdoor temperature is lower than the temperature of your exhaust air, you’ve made your house even colder than it would have been if you had exhausted the heat-pump inside your house.

Not only that, but the exhaust fan will have to work a little harder (and use a little more electricity) to send the exhaust air through ductwork than it would to just blow the air in your utility room.

How much will I save?

Robb Aldrich calculates that a family in New England could save between $40 and $270 per year by switching from an electric-resistance water heater to a heat-pump water heater. That calculation is based on a family that uses 35 gallons of hot water per day, with an electricity cost of 17 cents/kWh. (If you pay only 8.5 cents/kWh, your savings will only be half as much, of course.)

The low end of the savings scale ($40 per year) is for a heat-pump water heater installed in a bad location (a small, cold room). The high end of the savings scale ($270) is for a unit installed in a good location (a large, warm room).

According to Aldrich, the incremental cost to install a heat pump water heater (compared to an electric resistance water heater) varies from $1,400 to $2,700, depending upon which model was installed.

One of the reports that was issued by the Steven Winters researchers — “Measure Guideline: Heat Pump Water Heaters in New and Existing Homes” — includes a table with somewhat more optimistic conclusions that those summarized by Aldrich during his presentation. (Presumably, the optimistic assumption is based on avoiding bad installations in small, cold rooms.) According to the optimistic assumptions, a family using 35 gallons of hot water per day can expect annual energy savings of 1,750 kWh. If electricity costs 12.6 cents/kWh, the annual saving is $221, and the payback period is 6.6 years (based on a relatively low incremental cost of $1,458 to install the heat-pump water heater).

Families that use more than 35 gallons of hot water per day can expect a shorter payback period.

Choosing a heat-pump water heater

When it comes to integrated heat-pump water heaters — that is, units that come with a tank — five models dominate the market:

1.  AirGenerate makes the ATI50 (with a 50-gallon tank) and the ATI66 (with a 66-gallon tank). The larger unit costs about $1,900 to $2,000; it has an EF of 2.40 and a first-hour rating of 75 gallons.

2.  A.O. Smith makes the Voltex in two sizes (60 gallon and 80 gallon). The larger unit costs about $1,850 to $2,100; its EF is 2.33 and its first-hour rating is 84 gallons.

3.  General Electric makes the GeoSpring. It has a 50-gallon tank and costs about $1,200 to $1,500. Its EF is 2.35 and its first-hour rating is 63 gallons.

4.  Rheem makes the HP-40 (with a 40-gallon tank) and HP-50 (with a 50-gallon tank). The larger unit costs about $1,300; it has an EF 2.0 of and a first-hour rating of 67 gallons.

5.  Stiebel Eltron makes the Accelera 300. It has an 80-gallon tank and costs about $2,400. Its EF is 2.51 and its first-hour rating is 78 gallons.

All of the researchers I talked to emphasized the benefits of a large tank size, so don’t buy the G.E. unit, the Rheem unit, or the smaller AirGenerate unit. “Bigger and hotter tanks are better,” said Aldrich. “It’s counterintuitive.”

According to “Measure Guideline: Heat Pump Water Heaters in New and Existing Homes” by C. Shapiro, S. Puttagunta, and D. Owens, “The units with smaller tanks demonstrated difficulty in maintaining hot water delivery in high demand situations, even if their electric resistance elements are used.

The units with larger tanks provide a buffer in times of high demand and therefore are expected to use their heat pump for recovery, rather than reverting to electric resistance heating to maintain outlet temperature. The result is more efficient operation and better performance in terms of availability of hot water. In households with more than two occupants, a HPWH with a larger tank will likely be a better option.”

One other factor to consider: only one manufacturer (AirGenerate) makes a heat-pump water heater with a stainless-steel tank. The material used by the other four manufacturers is enameled steel. In most cases, stainless-steel tanks last longer than enameled-steel tanks.

How long will they last?

We don’t yet know how long the current generation of heat-pump water heaters will last. Nor do we know which parts will fail first — the controls, the compressor, or the tank.

When I asked Aldrich about the longevity of these units, he said, “That’s a big question. I am cautiously optimistic. Ten or 12 years ago, we did a study of the early models available, and we noticed failures during the first few years after the units were installed. We are not seeing anything like that now with the newer units. The controls are more robust. If you think of a refrigerator, how long does a fridge last?”

So I asked a follow-up question: “Well, would you put one in your own house?”

He answered, “If I didn’t have natural gas — yes, I would.”

original article at    greenbuildingadvisor.com

Window Performance

Warm weather is here and many consumers are looking to make home improvements while sticking to a budget. BBB ( Better Business Bureau ) advises consumers to balance cost effectiveness with energy efficiency, as more efficient windows, doors and skylights can make a big difference in energy consumption over time.

Start by looking for products that carry the Energy Performance Ratings label from the National Fenestration Rating Council. The label can help determine how well a product will perform its key functions – helping to keep your home cooler in the summer and warmer in the winter, keeping out wind, and resisting condensation.

As with any home improvement project, it’s important to make sure you deal with a reputable contractor and reputable materials. In the past year, the BBB serving Northern Colorado and Wyoming received 3,163 inquiries and eight complaints about window companies in its 38-county service territory and another 891 inquiries and no complaints about window installation companies.

When it’s time to purchase new windows, keep the following in mind:

1.  Check the window’s U-Factor.

During cold winter months, you want your windows to trap heat. U-Factor ratings generally fall between 0.20 and 1.20. The lower the U-value, the greater a window’s resistance to heat flow and the better its insulation value.

Retrofit for Energy Savings

2.  How much solar heat?

The Solar Heat Gain Coefficient rates how much solar radiation is admitted through the window. SHGC is expressed as a number between 0 and 1. The lower a window’s SHGC, the less solar heat it transmits in the house.

3.  Do you want lots of light?

Visible Transmittance is an optical property that indicates the amount of visible light transmitted through the window. VT is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted.

4.  Thwart unwanted breeziness.

Heat loss and gain occur by Air Leakage through cracks in the window assembly. The lower the Air Leakage, the better the window is at not letting air pass through cracks in the window assembly.

5.  Ensure windows are free from any water leakage.

The higher the Condensation Resistance rating, the better that product is at resisting condensation formation. While this rating cannot predict condensation, it can provide a credible method of comparing the potential of various products for condensation formation. CR is expressed as a number between 1 and 100.

Original Article at http://wynco.bbb.org

Phillips Takes the Lead

As a way to help conserve the environment, power conservation is one of the way to achieve that and it looks like our home electronics will be playing a part in helping us do that. Last year, the US Department of Energy challenged inventors to come up with a low-cost, but highly-efficient incandescent light bulb that would ultimately replace the 40 watt incandescent light bulbs that will be banned come 2014.

Philips took the prize home with their LED lightbulb that not only boasted an extremely impressive lifespan of 20 years, but it would only burn 10 watts of electricity.

The good news is that come this Sunday, the environmentally conscious will be able to start replacing their light bulbs with Philips’. According to the rules of the competition, the light bulb will have to hit a price point of $22 within its first year of availability.

The light bulb was originally priced at $60, although Philips has since discounted it down to $50 and are working with utility companies to offer rebates of $20-$30 to hit that $22 mark. In any case, the LED lightbulb will go on sale this Sunday but if they’re still a bit too expensive for your tastes, compact fluorescent lamp bulbs will offer up the same energy efficiency at a much more affordable $5.