This is a type of heat pump which utilizes outside air to heat or cool an interior space. They are more efficient than many heat pumps, but less efficient than ground-source heat pumps. However, they are cheaper to install than ground-source heat pumps, and have become widespread in recent years.

Air-source heat pumps work best in more moderate climates. Extended periods of below-freezing temperatures make the pump work too hard for it to be very efficient.

Most air-source heat pumps are split-systems: they have one copper coil indoors and one outdoors. The supply and return ducts are connected to a central fan also located indoors. Some air-source heat pumps are packaged systems. These usually have both coils and the fan outside with the air delivered through duct-work in the wall or roof.

Air-source heat pump efficiency is indicated by the HSPF (Heating System Performance Factor) and the SEER (Seasonal Energy Efficiency Ratio).

• HSPF is the rating for the system’s heating efficiency. The most efficient systems have an HSPF rating between 8 and 10.
• The SEER rates the pumps cooling efficiency. Usually the higher the SEER the more expensive the system. The most efficient pumps have a SEER between 14 and 18. This rating is more important than the HSPF in warmer climates.

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Proper shading can significantly reduce the load on your air conditioning unit, thus reducing the expenses too, in the summer months. Here are a few ways to landscape with efficient air conditioning in mind:

• Shading the unit itself can increase its efficiency by 15%! If you plan to do this however, leave 3 feet or so around the unit to allow adequate air flow. Trees and shrubs work here.

• Shade windows either with trees or vines. Direct, or nearly direct, sunlight coming through windows is a major source of heat in the summer; this causes the air conditioning unit to work a lot harder.

• Shrubs, vines, and trees can shade the sides of the house. This eliminates direct sunlight, and has a cooling effect in the surrounding area.

• Vines have the advantage of being able to get closer, more safely, to the house. They can go on trellises around windows and provide better shade than more distant trees.

• Deciduous trees are best on the south and east sides of the house whereas evergreens work better on the north and west.

• Medium to large trees should be planted 15-20 feet from the side of the house and 12-15 feet from the corner for the most efficiency.

Landscaping can be purely aesthetic, or you can turn your design into something that will work for you as well as being a beautiful addition to your home.

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Windbreaks are very important to your home’s energy consumption; they can reduce winter fuel expenditure by up to 25 percent! Several things determine the effectiveness of the windbreak:

Where and how the windbreak is placed: Obviously this plays a large part in the effectiveness of your windbreak. In most areas of the United States the prevailing winter winds are from the north and northwest, so every effort should be made to plant your windbreak with that in mind. The break should be placed at a right angle, or a u-shape, along the north and west sides of your house. The tallest row of trees should be closest to the building, but without being close enough to crush it.

The number of rows in your windbreak: While one row is good, more is better. Wind may be slightly diverted or slowed by one row of trees, but if it has to go through more it will be much more effective. If you have more than one row the trees should be staggered for an even better windbreak.

The types of plants: White pines are a common tree for windbreaks because they grow fast. However, as they mature they begin to thin out their lower branches which, as I mentioned in the previous article, isn’t good. If used with another type of tree or shrub , though, they can be very effective. In general, you want a dense tree that grows quickly and matures about 50 percent taller than the house. Before you plant any single variety be sure that it will grow well in your area. When there is not enough room for trees as a windbreak vines can be used instead. Clinging vines work well for masonry walls, but you’ll have to use trellised vines for walls with wood siding.

Having said all this, it is ever important to consider your own microclimate. It may be that your piece of land has an unusual layout, and its prevailing winds come from the south. Or maybe the land is a bit swampy and evergreen trees don’t grow very well in your area. Try to read your land and work with it, not against it. Everything will grow better and be more effective in the end.

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Smart landscaping can dramatically reduce your heating and cooling costs. However, there are several things to take into consideration when designing.

Climate: Even among different climates there are a couple of common things you can do:

• Maximize shade in the summer to reduce the cooling loads.
• Use windbreaks to block your house from winter winds.

Still, climate is something you need to consider. If you’re in a cool climate you may not want as much shade, even in the summer, but if you’re in a hot-humid climate you’ll probably want all the shade you can get in the summer. (More information on specific climates here.)

Microclimate: This is the plot of land where your house is situated. Taking this into consideration is almost more important than your regional climate; it will help determine what and how you plant.

Shading: This is especially important to consider if you’re in hot-humid, and arid climates; however, it’s important wherever you are. Shading the roof and windows will help the air conditioning load on your home. Vines on lattices can help shade windows, and groundcover can cool the ground and pavement around the house so the air isn’t so hot when it hits the walls and windows.

Windbreaks: Windbreaks can effectively reduce the wind chill. They are also a good idea if your home is air conditioned all summer and your climate has warm winds. The best types block wind close to the ground.

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First of all the word photovoltaics (PV) has two parts: Photo (the Greek word for light) and Volt (relating to electricity). In that way it really means light-electricity, which is pretty much what it is. PV systems take light energy and convert it into electrical energy.

The most common types of PV systems are based on silicon which, when arranged into a PV cell, creates an electrical current when sunshine hits it. The highest efficiency for silicon is held by monocrystalline silicon, and the lowest by thin films. Monocrystalline silicon is silicon sliced from a single grown crystal, and thin films are PV to which an amorphous film has been applied.

The major drawback to PV-powered homes is the start-up cost. It is really expensive to install a PV-system, but the pay-back is fairly quick depending on the area you are in, the federal and state rebates, and the size of the system itself. PV-systems are expected to have a life span of 25 years or longer. Maintenance costs are fairly low.

Not all PV-systems are the big solar panels on top of roofs. There are a growing number of building-integrated photovoltaic products (BIPV) that are allowing designers to disguise the systems within the roofs. Some are made to look like shingles, and some are made to work with roofing materials. The possibilities are endless!

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Below is a brief, helpful summary of the five main types of water heaters available, based on information from the Department of Energy. Future articles here will provide more specifics about each type.

 

1. Conventional storage water heaters

This type of water heater has a storage tank full of (usually) ready-to-use hot water.

 

2. Demand water heaters (also called tankless or instantaneous)

These heat water on-demand; no storage tank is required.

 

3. Heat pump water heaters

Heat pump water heaters take heat from another source, such as the surrounding air, and put it (at a higher temperature) into a tank where it will heat the water.

 

4. Solar water heaters

Obviously, these heat water with heat from the sun.

 

5. Tankless coil and indirect water heaters

This type heats water using the space-heating system in the home.

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So, what does that plastic-y, paper-y stuff on the outside of your house, underneath the siding, really do? If installed correctly, housewraps perform three functions critical to energy costs, comfort, and, over time, structural integrity. Those functions are primarily: act as a second weather barrier (prevents wind-driven rain from getting any further into your home), serve as an air barrier (thus lowering energy costs), and allows interior moisture to escape (vapor-permeable membrane, VERY important!).

Now that we understand what housewraps do, how do we choose from the dozens of varieties on the market? Well, of course there’s no easy answer. Siding sometimes helps determine what wrap to use: vinyl siding comes with built-in drainage holes and wouldn’t need the same type of wrap as brick, stucco, or board siding. If, however, the siding is no help whatsoever in coming to a conclusion the perm rating may help. Permeance ratings reflect the measure of a material’s ability to transfer water vapor. So, the higher the perm rating the faster interior moisture can escape. However, this does not always mean it’s better. Some wraps are perforated to obtain a high perm rating, but the perforation allows exterior moisture in! Not good.

Depending on the type of siding you’re using, it could affect the housewrap’s weather resistance. Cedar and redwood both leech surfactants (surface-active contaminants) which increase water’s ability to pass through the wrap. Not only the siding, but also power-washing chemicals, soaps, and even some types of paint can reduce your home’s efficiency and protection.

Installation is extremely important too. Working from the ground up, vertical and horizontal joints should have sufficient overlap: 12 inches for vertical, 6 inches for horizontal. Also, all joints should be taped with special housewrap tape. Even the nails used are important. The nails most housewrap manufacturers recommend are plastic cap nails.

Once again, much of the information in this article can be found here.

Settling occurs over time on all houses, and, as a result, the original weatherstripping can wear out, creating small cracks around movable joints. These small cracks are huge energy guzzlers; they can account for up to 40% of a home’s heat loss! There are many types of weatherstripping, and different seals have different uses.

Rigid Jamb: This weatherstripping has a metal or vinyl flange that is attached to a tubular section of vinyl or rubber. Higher quality versions are filled with silicone or foam, giving even better insulation and helping the seal keep its shape. This weatherstripping is installed by nailing, stapling, or screwing the flange into the the joint. The cost is 50¢ to $2 a foot.

V-strips: This type of weatherstripping is sold in rolls of bronze, vinyl, stainless steel, copper, and aluminum. The adhesive-backed strips are easiest to install; however, the metal ones, which have to be installed using driving brads hammered in every 3 inches, hold up better. This costs $1 to $2 a foot.

Felt: Felt weatherstripping of various thicknesses, widths, and colors comes in rolls. This, like the v-strips, can be either pressure-sensitive or nail-on. Some varieties come with a flexible vinyl or metal backing which increases efficiency. However, this weatherstripping wears out quickly (It can snag and catch easily.), and is relatively inefficient compared most other types of weatherstripping. It is cheap though–approximately 13¢ a foot.

Pressure-sensitive, adhesive-backed tapes: These tapes come in several forms: non-porous, closed-cell foam, open-cell foam silicone, and rubber. They are available in various thicknesses and lengths. EASY installation! Just peel and stick on a clean, dry surface, with perhaps an occasional tack or staple. This should be used only on parts that aren’t opened, such as the upper sash of a window. The cost is anywhere from 20¢ to $1.15 a foot.

Kerf-in: A kerf is a blade-width notch cut into a door or window jamb with a saw or router. So, this type of weatherstripping is silicone, plastic, or foam pressed into this notch. This is an excellent option for weatherstripping, and relatively inexpensive at 18¢ a foot for plastic, 38¢ for foam, and 35¢ to $1.10 for the better-insulating silicone.

Interlocking metal: This weatherstripping, as the name implies, comes with two pieces that interlock to form a seal when the door (which is what this is used for) is closed. It is more efficient, more expensive (at $1.50 to $3.00 a foot), and more difficult to install than other types. It’s probably best to let the experts install this.

The information in this article was borrowed heavily from here.

Single-glazed, double-glazed, and triple-glazed windows are all options.

Single-glazed windows: These are best for places like garages and sheds that need minimal insulation.

Double-glazed windows: These are windows with two panes of glass with air or (more commonly) a colorless, odorless gas, usually argon or krypton. This can get an R-value of R5 when the glass is treated with a low-emittance (Low-E) coating.

Triple-glazed windows: This is pretty much like double-glazed windows except the gas is sandwiched between three panes of glass. This is a very efficient option achieving an R-value up to R10!

Here are a couple of sources that show how to glaze windows on your own:

• http://www.ehow.com/how_2054616_glaze-window.html
• YouTube video (not great quality, but it shows how to do it more or less)

(Source: This one has many more glazing options than I went into here.) (Source)

Some information about a water heater is easy to find on labels if you know where to look and how to interpret it.

ENERGY STAR. Do not look for an ENERGY STAR label. The U. S. Department of Energy is working on creating an ENERGY STAR residential water heater program, but at this time (latest information found is from October, 2007), the ENERGY STAR program does not address water heaters. As a matter of fact, “water heating is the only major residential energy end use that the ENERGY STAR program does not address.” (source 1)

Price tag. Most, if not all, major appliances have two price tags: one shows the purchase price; the other, the lifetime-operating cost of the appliance.

EnergyGuide label. Most appliances have an EnergyGuide label (a bright yellow and black label that tells the operating cost of the appliance) so that the consumer can easily compare different models and make a more informed purchasing decision.

The first-hour rating (FHR), or recovery rating, of a water heater can be found on the EnergyGuide. (source 2). Indicating the amount of hot water that the water heater can deliver during peak hot-water use, this information is actually more important than the more-commonly considered tank capacity. (source 3)

Energy Factor (EF). Often listed beside the EnergyGuide, EF is a measure of the efficiency of the water heater, taking into account recovery-efficiency, standby losses, and cycling losses. The more energy efficient the water heater, the higher the EF.

Water heater label. Labels on water heaters vary, but some of the information often included are manufacturer; model and serial numbers; R-value (insulation rating); capacity; manufacture date; and the Btu input rating, which indicates how powerful the water heater is. (source 4)

Several materials are used to make window frames: Wood (including vinyl-clad), aluminum, vinyl, and fiberglass. Wood and hollow vinyl being the most common.

Wood: These are typically the most expensive frames. They can be either solid wood, vinyl-, or aluminum-clad. The big drawback to solid wood is the frequent maintenance it requires. Vinyl- and aluminum-clad frames are by far the most popular. They require much less maintenance than solid wood, but the exterior color cannot be changed without replacement.

Vinyl: Vinyl frames are everything that solid wood frames aren’t: rot-proof, weather-proof, and insect-proof. However, these, like the wood-clads, have aesthetic drawbacks. Over time vinyl frames fade. They also move a lot, but they are built with that in mind.

Fiberglass: These frames are more expensive than vinyl, and they have the same u-value. It also must be painted. Fiberglass frames are relatively new to the market.

Aluminum: Aluminum frames are not efficient at all! Though they are the third most widely-used window frame today, they are a very distant third, claiming only 17% of new home window frames. On the flip side, they are every durable and require very little maintenance. Still, it’s probably best to stay away from these, if you have a choice.

U-factors:

• Aluminum: 1.0-2.2
• Aluminum-clad wood: 0.4-0.6
• Wood and vinyl: 0.3-0.5
• Fiberglass: 0.2-0.3

(Source) (Source)

Replacement windows, repair windows, window frames, window sashes, window glazes, smart windows! R-value, U-factor! AHHH! The mystery of it all is overwhelming, so let’s dispel some of it.

Well, first things first: the difference between R-value and U-factor. As we have seen elsewhere, the higher the R-value the more efficient it is; the U-factor is the opposite. The lower the U-factor, the greater the window’s resistance to heat flow, thereby making it more efficient.

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Replacement: Probably, you will only want to replace the entire window (frame, sash, and glass) if there has been water damage. Then you must determine and fix the point of that water damage. This is the most expensive method, considering labor. This will, however, give you more options than repairing, and is the most durable and energy-efficient.

Repairing: This is different than replacing the entire window. Perhaps the only thing that’s wrong with the window is that the sash or seal has started leaking. Or maybe you just want to upgrade your window’s efficiency without getting too involved.

• Replacing the sash: This repair method is easy and relatively cheap, and comes with the bonus of being an energy-efficient upgrade. However, it may be hard to fit a new sash in an old opening.
• Replacing sash and frame: This option is even more efficient than replacing just the sash because the sash and frame have been tested as an entire unit. This has a couple of cons though: it is the most expensive materially than either replacing the sash or the entire window, and it has a bulkier look because of an additional window frame.

That gets the most basic methods of repair/replacement windows. We’ll take a look at some of the materials later. (Source)

Heating water in a home, on average, uses 13% to 25% of the energy consumed in that home. Depending on your source of information, it is the second (1) or third (2) largest consumer of residential energy, being topped only by space heating and cooling, and possibly by kitchen appliances.

A number of factors should be considered when choosing a water heater, including (but not limited to) energy efficiency; type of fuel and its cost and availability in your area; size/capacity; cost, taking into account the purchase price and the cost of installation; and the space you have provided for the system. Your climate and environment, including the position of your home, should also have an impact on your choice, particularly when considering a heat pump water heater, a tankless coil water heater, or a solar water heater. Another factor is ease of installation: will this be in a new-construction or is it a retro-fit?

Among the types of water heaters available today are storage, or tank-type; tankless; demand (or instantaneous); heat pump; natural gas; propane; oil; electric; and solar, each type having its own advantages and disadvantages.

Future posts will examine the types of and considerations about water heaters in more detail.

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In the last article we discussed the different (most-common) types of sheathing for SIPs, but just as there are different sheathings there are also different foam cores. In this article we’ll look at the three main cores there are in the structural insulated panel industry: polyurethane, expanded polystyrene (EPS), and extruded polystyrene (XPS).

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Polyurethane: With 6 to 6.8, this foam core has the highest R-value per inch of the three I’ve mentioned. Another advantage is its high melting point; in a fire, it would be the last thing standing. However, polyurethane foam is expensive at nearly 40 cents per square inch of panel, Also, the hot wire burners that are used for on-site adjustments can’t be used because of the melting point.

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Expanded Polystyrene (EPS):EPS is the most common type of foam core for SIPs. It is cheap, widely available, and most installers are acquainted with it. However, like many readily available things, there are trade-offs. It has the lowest R-value and melting point.

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Extruded Polystyrene (XPS): XPS is a nice in-between when compared to the above two foams. It has a high R-value (5 per inch of panel) while still having a rather low melting point so on-site tweaks can still be made. Something this good has to have a bad point though, and this is no exception: XPS is expensive and hard to find.

Source.

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Let’s take a closer look at some of the various aspects of structural insulated panels. The materials that SIPs are made of make a difference in several ways. In the last article, I mentioned that SIPs could be made of OSB, metal, cement-board, and fiber-glass.

OSB: Oriented Strand Board is made from sustainable fast-growing trees, and is the most common type of sheathing material for SIPs.

Metal: Stainless steel and G90 galvanized are the most common metal sheathing used for SIPs. Long-term it’s probably best to go with stainless. (Source)

Cement-board: Typically made of cellulose, reinforced, cement boards, the fire-resistance eliminates the need for gypsum drywall. These are so strong that headers above the windows and doors are unnecessary. They are generally as efficient as OSB panels. Cement-board SIPs typically last longer and require less maintenance than other types of SIPs. They also have good resistance to moisture absorption. This type of sheathing is slightly more expensive than OSB SIPs. (Source)

Fiber-glass: Fiber-glass sheaths are bonded to PVC or studs for support, and consist of polymer-based resins blended into a reinforcing frame of structural glass fibers. The sheaths are thin, but quite strong. (Source) (This one is not nearly as common as the previous sheathing materials mentioned.)

What are SIPs? SIPs, or structural insulated panels, are composed of a thick, rigid-foam core sandwiched between two sheets of OSB (Oriented Strand Board), metal, cementboard, or fiberglass. Created to be a high-performance, energy-saving building material, SIPs can be custom designed for each home.

Cost of SIPs? SIPs construction costs about the same as traditional construction when you figure in the labor savings for a shorter construction time. SIPs allow the HVAC to be smaller, which would also bring savings during the construction period. However, the greatest savings will be through the years with reduced energy bills (even up to 50%! source)

The History of SIPs: SIPs aren’t new. In fact, Frank Lloyd Wright used them in some of his Usonian houses in the 1930s and ’40s. When one of his students, Alden B. Dow, the son of the founder of Dow Chemical Company, created the first foam core SIP in 1952, SIPs jumped into the technological world. In the ’60s, SIPs became readily available, resulting in the building material we know today. (Source)

Wiring SIPs: As could be expected, wiring is different with SIPs. The manufacturer cuts chases, or channels, according to the house design during the manufacturing process, through which the wire is pulled.

So what is the big difference between compact fluorescent lights and traditional incandescent? Well, it seems that the differences go on and on forever so let’s consider the differences from an energy cost perspective. For a given light output, CFLs use between one fifth and one quarter of the power of an equivalent incandescent lamp (source).  This is because  typical incandescent bulbs convert only about 10% of the energy they consume into visible light while the remaining 90% becomes heat! By comparison CFLs waste only 30% of the energy they consume in the form of heat. But what does this really mean and how does it affect me? It means that you can often replace the typical 60 watt incandescent bulb with a 15 watt CFL and that, when installed throughout your house, will have a measurable affect on your monthly electric bill. But wait, there’s more! Since CFLs emit less heat, during summer months your air conditioning unit will have an easier job keeping the house cool.

Of course there are often trade-offs with every Energy Smart Idea we consider. CFLs are not the final solution to our energy consumption woes and they’re not appropriate in every situation. We’ll consider some of the down sides in another article.