Friday, July 16, 2010

Solar Thermal Water Heating Systems

Ever want to use the sun to heat your water? If you have you are not alone. Solar water heating got its start in 1767 when Horace-Benedict de Saussure discovered the green house effect. He observed that it was always hotter when the sun light passed through a glass covered structure, such as a coach or building, than it is when it passes into an open area. He went on to prove this theory by creating a box that is very similar to today’s panels for a solar water heater.

While the De Saussure discovered the science behind today’s solar water heaters it wasn’t until 1891 when Clarence Kemp became the first person to patent a solar system that solar water heating came to the masses. The first system was a simple system called the Climax that heated the water using an insulated box that contained metal cylinders covered with glass. This system was typically mounted on the roof. Kemp originally marketed his units to the east coast but by 1897 1/3 of the homes in Pasadena, California had solar water heaters.

The invention and use of solar water heaters continued to climb until the 1920’s when the discovery of natural gas began the gradual decline of solar water heaters. After World War Two the increased cost of materials and decrease electrical rates the use of solar water heaters was effectively killed. It wasn’t until the energy crisis of the 70’s that the use of solar water heaters began to rise but this was short lived as in the late 80’s we experienced a second drop off.

In the past few years we have experienced another rise in the use of the solar water systems. This is due to the increase in energy cost and individuals consciousness of their environment. As the interest in solar thermal systems increase the general public’s need for knowledge about the systems also needs to increase. For that reason we will review some of the different types of systems that are available today.

Solar systems can be classified by the combination of two classification groups:

1. Water heating: This classification focuses on two different ways of heating the water.

a. Direct: The water is directly heated by the sun

b. In Direct: A transfer fluid is heated by the sun and transfers the heat to the water. In this case the water is never directly heated by the sun but rather a transfer fluid.

2. Water Movement: This classification focuses on how the water or transfer fluid is moved in the system.

a. Active: The water or fluid is moved using pumps and electricity.

b. Passive: The water moves using the natural properties of water in which cold water falls pushing warm water up creating a current or flow.

By combining either of the classifications from group one with group two you can define every type of solar water heating system on the market. While these classifications can define all types of heaters there are some types that are more prominent than others.

Drain Back System: (Active In-Direct) This system is one of the most common because it has very good freeze and over heating protection. This unit uses water as the transfer fluid and will drain the water out of the solar panels when it is not heating. This way during times of freeze or inactive use the unit does not have water in the panels. These units do use more power than other units and they can be noisy due to the need for larger pumps.

Pressurized Glycol System: (Active In-Direct) This system uses propylene glycol as the transfer fluid. These units use the glycol as the freeze protection of the system. The pumps are smaller because the fluid is pressurized and because of this a PV panel can be used to run the system. The disadvantages to this system are primarily due to the use of glycol as the transfer fluid. There is a reduction in the efficiency of the fluid to transfer heat and maintenance can be required to ensure the fluid has not deteriorated.

Drain Down System: (Active Direct) This system differs from the above systems in that it directly heats the water that is used. The system is not as complicated as other systems and the heating efficiency is good. The downfall of this system comes from the freeze protection. This system must be manually drained and refilled every time the temperature falls to a point in which the water could freeze. Also the water for the home must be good so that it doesn’t cause corrosion and mineral deposits in the system.

Direct Thermosyphon: (Passive Direct) Passive systems are the simplest systems on the market. Passive systems can use a storage tank and panels or heat the water in the tank itself. A thermosyphon system uses panels and a tank. The panel is installed below the tank and uses the natural flow of water to move the hot water into the tank for storage. As the water cools off it falls to the panel to be heated again. Passive systems are simple and reliable but they can be unappealing to some individuals.

Each unit has its application based on the site and user preferences. Prior to purchasing a unit it is highly recommended that you consult with a knowledgeable installer and have you site assessed to determine which unit is best for you.

Reuse your spray foam cans.

Spray foam is a great addition to your tool box when sealing up your home. One of the largest problems is that you can’t keep it in your tool box after you have used it. This is because the tip is hard if not impossible to clean once it has been used once. With this little tip however you can return the can to your tool box after the first use. Keep some tubing in your box as it can be used as the tip to the can. The tube can be a recycled such as the outer liner to 2 wire electrical wire or it can be water line tube with the correct inside diameter to fit over the can tip.

Friday, June 4, 2010

What HVAC system should I use?

In most homes the HVAC energy use makes up the largest percentage of the home’s energy consumption. This information is becoming common knowledge as more individuals become energy savvy but many individuals still wonder which system is the best for them. There are various systems that can be used to heat the home but as certain system types are being phased out due to technology, such as boilers, other are beginning to rise to the top. These systems are heat pumps and furnaces. In most cases people are familiar with these systems but they may not realize which is better for them or what the differences in them are.

The first bit of information that a homeowner should understand about a system is that no matter what system is installed it should be installed properly. This is especially critical for the air conditioner. All systems must be sized and designed properly to provide quality and efficient heating and air. To start a load calculation must be performed. This is referred to as a Manual J calculation. Beyond sizing the system the ducts and registers must be sized to the system to properly provide conditioned air to the home. This is a lengthy process and for more information regarding proper installation please refer to my previous blog Why HVAC isn't just a lot of hot air .

Your system selection will depend on your climate location but here is some information about each popular system type.

1. Air Source Heat Pump: Air source heat pumps have the benefit of providing both heating and cooling function and are essentially an air conditioner that can work in reverse. Heat pumps do not create heat but rather transfer it from place to place. For this reason they are extremely efficient and can actually transfer more energy than what they consume. Air source heat pumps draw their energy from the outdoor air. Because of this they are not appropriate for areas of extreme cold. Also heat pumps can require a back up heat source for colder days. This is typically done with an electric backup. This electric back up can be extremely costly and therefore should be avoided as a heat source much as possible.

2. Hybrid Systems: A hybrid system is an air source heat pump with a gas backup. This is a good system for areas in which a heat pump is a good choice for the majority of the time but there may be short periods of extreme cold in which the backup heat strips on conventional heat pumps my run for extended period of times. Hybrids are most efficient in transition areas between warm climates and cold climates.

3. Ground Source Heat Pump: Ground source heat pumps work exactly the same as air source heat pumps but they draw their energy source from the ground. Since the ground stays at a constant temperature the heat pump is able to be more efficient. Ground source heat pumps are more expensive than air source heat pumps and extremely efficient air source pumps can come close to the same efficiency as low efficiency ground source systems. One bonus to ground source systems is many of them have the ability to heat water as well.

4. Furnaces: Furnaces are generally efficient than heat pumps but they are better in cold climates. This is due to heat pump efficiencies decreasing as the outdoor temperature decreases. Heat pumps require the use of electric heatstrips to make up for this deficiency.  Due to this furnances are a better fit in the colder climates.  In considering a furnace one must consider the climate they are in and if it is a better fit than a heat pump for their home.

5. Mini Splits: Mini splits are the same as air source heat pumps but they do not require the installation of ducts. This has several benefits especially for retrofits. Small units are placed in each conditioned space and can be individually controlled. By eliminating ducts you also eliminate the losses associated with ducts.

6. Air conditioners: There are little options available for air conditioners. If you are not using one of the heat pumps you must also install an air conditioner. If you are in a climate in which you must install an air conditioner choose one that has the highest efficiency appropriate for your area. For areas in which cooling is only needed for a few days a year an extremely high efficiency system may not be appropriate where as in areas of extreme heat the highest efficiency system will have a relatively quick payback.

Don’t turn up your thermostat more than 2 degrees at a time.

While this really only applies to heat pumps it is good information to know. By turning up the temperature more than 2 degrees the heat strips on the system will cut on. This is extremely expensive heat and will quickly run up your electric bill. If you have a programmable thermostat make sure you have one with adaptive recovery. This will prevent your system from trying to raise the temperature too much as one time and cutting the heat strips on.

Sunday, May 23, 2010

When Windows are an Appropriate Selection

With the onset of energy-conscious consumerism, there has in turn been the creation of energy-oriented marketing campaigns. One of the most prominent campaigns has been those of window manufacturers and installers, with most of these campaigns focusing on window replacements. There have been varied opinions on whether the replacement of windows is warranted. Ultimately, the numbers prove that unless your windows are extremely leaky or in disrepair the replacement of windows has an extremely long payback. This extended payback makes window replacement one of the last items on a proper energy conservation list of improvements.

However, window installation in new homes takes on a different perspective. Due to windows playing a large part in the energy consumption in a home, they are one of the most important factors to consider when building a home. This may seem counter to the above perspective, but one must consider that when building a new home, one must install windows. The additional cost for improved and more energy-efficient windows are minimal compared to the amount of savings they will produce.

In new energy-efficient construction, window selection should be considered just as important as selecting your HVAC system or site layout. For that reason, it is important for you to understand the different types of windows available.

While there are many different types of windows, and their structure affects how they function, there are basic components common to each one. Besides the type of window, to make a wise decision in selecting windows, one must understand the basic components of a window. These are the frame, glass, spacer (for multiple pane windows), coatings, and gas fill.

Gas Fill

The frame is the material around the glass, and essentially makes the window. The frames can be made from various materials, and the frame material affects the amount of heat the unit can conduct around the glass. There are several different types of frames and they range greatly in price.

Wood frames have long been considered a sign of quality and performance. There are some issues with wood frames, such as the susceptibility to rot. This has been improved by cladding the exterior with aluminum or vinyl. Overall wood frames are a good selection, especially with the cladding. The U-Factor of the frame is around 0.3 to 0.5. (The lower the U-Factor, the better, when selecting a window)

Vinyl has been a mainstay for cost conscious builders and for this reason come in a wide range of quality. Vinyl is similar in U-Factor as wood and does not have the problem with rotting. However, vinyl does expand and contract greatly, affecting the leakiness of the window; in lower-quality windows, vinyl can degrade with exposure to UV light.

These frames are stable and energy efficient. The frames can even be filled with foam to increase the efficiency. The U-Factor of fiberglass frames range between 0.2 and 0.3.

 Avoid them! While aluminum windows are available, they should be avoided for new construction.

Glazing is simply the glass in the window. Glazing can be found in single, double, or even triple pane. Each additional layer of glass increases the efficiency of the window. To truly take advantage of the window panes, the spacing between panes needs to be at least ½ “.

The most common coating is Low-E. This works by reducing the amount of infrared energy that enters the home. The coating reflects the energy away from the home. Additional improvements can be made to the coatings by using Heat Mirror technology. This is film adds additional surfaces for Low-E coatings and creates the effect of triple glazing. 

Gas Fill
Gas fill helps reduce the convection heat transfer in the glass. The temperature difference on the glass can create convective flow within the panes of glass. This movement of air and transfer of heat can minimize the benefits of multiple pane glass. By adding heavy gas into the spaces the potential for convective loops are reduced.

Spacers are what separate the panes of glass and are often overlooked. There is little that needs to be known about spacers other than when possible select a spacer that has a lower conductivity.

The better the combination of these components the more efficient windows will be. There are even windows being developed that will have R-values close to those of the walls they are placed in.

Install your windows correctly!
There is more to installing windows than just setting the unit into the opening. One must properly seal, flash, and set the window. When installing a window, ensure that you have the window properly set into the opening, the window and opening is flashed to prevent water intrusion, the building wrap is properly installed around the window, and the gap between the window and the rough opening is properly insulated. Having an efficient window does you no good if it is poorly installed!

Saturday, February 27, 2010

Basics of an Energy Audit

In this era of energy conservation and sustainability the home energy audit is quickly becoming a common service. What many people don’t realize is that this service has been around for several years but it has just recently come to the attention of the mainstream media. With this new found attention, like many of the sustainable services, the demand for energy audits is increasing at an accelerated pace.

With this increase in demand and as you may be considering using this service yourself it may be beneficial for you to learn a little bit about the basic ideas behind the energy audit. This includes a few terms, the purpose of the audit, the main goals and what knowledge a auditor must have to perform the task.

Two Important Terms

There are two main trains of thought typically considered when discussing energy use. The first of these and the most commonly used terminology is energy efficiency. Energy efficiency is the thought of giving consideration to maximizing the economic benefits of wise energy use. Examples of this would be the purchasing of more energy efficient appliances, CFLs or a higher SEER HVAC system. While this is the more common term these improvements tend to require a larger investment at the beginning.

The second train of thought is energy conservation. Energy conservation is the process of reducing non-renewable energy use and its resulting environmental damage. Conservation includes items such as behavioral changes and improvements that reduce your energy consumption such as insulation upgrades. The improvements in this category will typically have very short payback periods.

When considering recommendations improvements in both of these categories are important. It is the auditor’s responsibility to consider all the improvements and create a comprehensive plan outlining these improvements for the homeowner. In order to do this the auditor must first understand their purpose when performing the audit and the major goals.

The Purpose of an Auditor

When performing the audit an auditor is to objectively perform certain task. These tasks may vary slightly in execution but in the end an auditor should perform all of these items with the possible exception of two. The most important concept of these tasks is that in order to perform them properly the auditor must perform them objectively.

1. Identify the energy consumption in the home.
- This is the main concept of the audit. The auditor is to view the home and determine the primary areas of energy consumption in the home so that recommendations can be made.

2. Note current and potential safety problems.
- An auditor must identify any health or safety issues in the home that they come upon. This is imperative as some problems such as combustion back drafting may be increased with recommended repairs. The auditor must also predict any possible issue that may arise due to performing the recommended improvement.

3. Recommend appropriate measures
- The auditor must formulate recommendations based on their findings and these recommendations should be made according to their payback, return on investment or carbon footprint reduction.

4. Estimate Cost
- Some auditors may help estimate the cost of repairs. While this step may be performed while determining the recommendations an auditor may not chose to supply the actual cost to the homeowner for various reasons.

5. Explain behavioral changes
- This is a key part of an audit. Behavioral changes are some of the most cost effective improvements a homeowner can make. While these may be very hard for an auditor to observe they can make some assumptions and make recommendations off of these.

6. Provide a written record
- An auditor needs to provide a written report of some form to the homeowner so they have a record of what improvements to perform.

7. Quality Assurance
- This is another step that the auditor may not perform. Depending on the wishes of the homeowner an auditor may return to verify repairs were performed properly.

Major Goals of an Audit

There are four major goals of the audit

1. Conserve energy, increase efficiency and save money
2. Reduce the carbon footprint of the home by reducing energy by products
3. Increase comfort in the home
4. Enhance the buildings health and safety

Use a low flow shower head

Low flow shower heads can help you save in two ways. The first is the most obvious in that it reduces the amount of water you use. For everyone on a public water system this reduces not only the cost of the water but the sewer charges as well. This can be beneficial to some people but others on a well may not see a monetary savings in this way.

The other method of savings is one that everyone can receive. This is savings through the reduction in water heating. As you use less hot water for showers you in turn can save in the heating cost of your water.

Many individuals will complain about the reduction of the water flow but several advancements have been made to minimize the perceived difference. This minor difference is certain acceptable considering the new shower head can potential reduce your consumption in half.

Saturday, February 20, 2010

How to seal your ducts

Your duct leakage can account for up to 20% of your leakage in your home. This is considerable amount in itself but is even more of a concern when you consider that in most homes the majority of the ducts are located outside of the conditioned space in the attic or crawlspace. The leakage into these spaces is costly and can create unwanted pressure differences in the home.

Locating the Leaks

The first step in eliminating the leaks in your duct work is to find them. This can be done in several ways but some are easier than others.

1. Visual inspection: All steps in finding the leaks will involve this process. You need to visually inspect the ducts to find any visible separations, penetrations or dislocations in the ducts. Some may be obvious while others may be hidden. Look for areas where duck tape may be failing (yes is it duck and no it should not be used to seal duct joints.), at locations where two ducts meet, around the boots in the floor or ceiling and at the trunk line.

2. Duct blaster: You can have a professional perform a duct blaster test on your duct work. This will let you know how much leakage is in the duct work but by itself it does not tell you where the leaks are. You can however have the professional use theatrical smoke to fog your duct work. This will allow you to see where the leaks are as the smoke will exit at the leaks.

3. Panning: Again a professional is needed for this. A professional will use a blower door and a pan to test your ducts to see which ones are leakier. This method can help isolate problem ducts but it does not have the ability to locate the leak itself.

Fixing the leaks

Once you have located the leaks you need to fix them. First you need a few supplies. These are:

1. Mastic- a material used to seal the ducts
2. Cheep paint brush-used to apply the mastic
3. Fiberglass tape-used with the mastic to seal the joints
4. Large zip ties- used to secure the inner and outer layers of the duct work
5. Duct-you may need to replace torn sections.

Duct Joints:

If you have leaks at the joints of the duct work you will need to seal these joints with mastic. This will be where the majority of your leaks are so this is the most common fix. First remove any old tape form the joint and then remove the outer layer of the duct. This is if you have a flex duct. If the inner plastic layer of your ducts is not secure you can use a zip tie to secure the inner duct. Next apply a large helping of mastic to the inner layer of the duct. You can then slip the outer layer back over the duct. Some individuals like to also secure the outer layer as well using the zip ties. You will then mastic the outer layer as well using the same technique you used on the inner layer. Make sure you pull the insulation (outer layer) over any boots or collars.

Disconnected Ducts:

If you have any fallen or disconnected duct work you will reconnect the duct work in the same manner as described in the above step.

Metal ducts:

This covers both the metal supply ducts and trunk lines. You will follow similar steps as in the duct joints section however you will use metal sheet screws to secure the duct if needed. Also you may have some gaps larger than ¼” and will need to use the fiberglass tape along with the mastic.

Torn ducts:

Unfortunately flexible duct work will tear. If this happens you may not be able to repair the duct and will need to replace the whole run or just a section. If you are repairing just a section make sure you use metal joints at both ends of the patch and use the same techniques as in the duct joint section.

Alternative methods:

There are alternative products and methods to sealing your duct work. These include mastic tape and foil tape. Mastic and mastic tape is best used on duct work but foil tape can be used to seal items that need to be routinely opened like your air handler.

There is also an alternative method of sealing that a professional can do. This involves spraying an adhesive/sealant through the duct work. The sealant finds its way into the leaks and seals anything up to a ¼”. This can be a cost effective way to seal the duct work if you have several small holes.

Don’t “crank” your dial on your thermostat.

Moving the temperature setting higher up on your thermostat does not make you home heat up any quicker. If you have a heat pump move your thermostat 2 degrees at a time to help conserve energy. If the thermostat setting is raised greatly the heat pump will use your heating strips to heat the home costing you a lot of money.

Saturday, February 13, 2010

How to seal plumbing and electrical penetrations

If you have been following along for the last few weeks chances are you may have already addressed the penetrations that we will talk about this week. Plumbing penetrations, vent fans, chimneys and other major penetrations may be obvious leaks or they may create leaks in other parts of the home and you don’t realize where the source is.

There are two types of leaks direct and indirect.

Direct leaks are leaks that occur directly at the wall penetration. An example of this may be a dryer vent or door.

An Indirect Leak is one in which the leak occurs at one location and the air exits at another. In this situation the air flows through holes and spaces in the wall cavity. An example would be a leak that occurs where a plumbing drain line enters the home but exits at an outlet.

Indirect leaks are one of the most common and problematic because you don’t know where the entry point is. To eliminate this you must seal all openings to the home.

Plumbing and Electrical:

In newer homes most of these penetrations will already be sealed due to code. However some may have been missed and there are a lot of older homes so we will visit how to correct them.

Electrical are the easiest. Using some fire caulk or silicone caulk depending on the situation you just have to locate the holes and put in some caulk. Fire caulk is required by code in new construction where wires or pipes penetrate floors and ceilings. If you have a larger hole you can use foam to seal it but in most cases electrical holes will not be much larger than 3/4”. Most of your penetrations are going to be in the crawlspace, basement or ceiling. Very few will be on exterior walls.

Plumbing penetrations may require a variety of fixes. If the hole is small, like with supply lines, you can caulk but if they are larger will need to use foam or rigid foam board to cover the gap. Foam will usually be fine around drain lines and vent pipes. You may find a large hole under your tub though. In this case you can use rigid foam board to cover the hole and use an adhesive or spray foam to affix it.

Vents and Fans:

If you have vent fans in your bathroom you are likely to have a large leak at this point. Often times the drywall will be cut larger than the fan box. This can be sealed using either spray foam or caulk depending on the size. Hopefully most will only need caulk but if yours needs spray foam (larger than ½”) then be careful because the spray foam may bend the fan housing if the metal is then.

Once you have the ceiling sealed you may need to look at the vent. Newer models will have a damper at the unit so that it closes and creates a seal from the outside when not in use. If yours doesn’t have this or if you still feel a leak you can install a damper in the vent at the end. This is rather easy if you can access the line as it exits the home. The dampers are rather inexpensive but they can help with this pesky leak.

Dryer vents and most other exhaust fans can also have the same problem and you can typically install a damper in them also to help out. If you do this make sure that it is not against building code or manufacturer recommendations.

Seal up your fireplace

Chimneys can be a major point of leakage in a home when the fireplace is not in use. In these situations you can do two things to help reduce this costly necessity. You can install air tight doors to prevent the chimney from drawing air out of the home or you can use a chimney pillow. The pillow is the less expensive fix and relatively easy to install. The pillow is inserted into your chimney and is inflated to seal up the opening. This prevents air from moving through the chimney when not in use. When you want to use the fireplace just pull the cord and remove the pillow.

Saturday, February 6, 2010

Sealing leaky doors and windows

Doors and windows make up about 20% of your home leakage. They are also some of the easiest leaks to find and most of the time the easiest to fix. There are however a few misconceptions when dealing with them though.

First let’s take on two misconceptions with the windows and then we will look at how to fix the leaks.

1. Not all that feels like a leak is a leak.

This is especially true with windows in the winter. Because of the properties of the windows what we truly fell is the heat radiating from our bodies and the convective flow created around the window due to heating and cooling of the air. The leaks are often time minimum around the window, usually around the joints between the jamb and sash. The largest “draft” or “leak” is created again from the thermal transfer occurring between the room, windows and our bodies. This leads us to “feel” a leak when one is not there. HVAC ducts are often times placed in front of windows to stop this from occurring but we often times place furniture over the ducts and prevent this effect. Below is a drawing showing the transfers.

2. It is not always better to replace than to repair a window.

I have discussed this many times before but to once again address this, payback on replacement windows can be anywhere from 15 to 30 years. This means it takes that long to get your investment back from the savings the windows create. A good pack is 0 to 5 years and acceptable 5 to 10. Also if replacement windows are not installed correctly you may end up with windows leaker than the ones you started with. If your windows are not in that bad of shape a little caulk, glazing and weather-stripping can get them back to new.

With that taken care of let’s move on to how to correct the leaks you feel. Most of the leaks you find are going to be around the joints in the doors and windows, this being the areas where the slabs or sashes join the jambs. This can typically be fixed with a little weather-stripping. Below is a diagram showing different types.


Most new doors have weather-stripping already installed but it can wear out sometimes. The best thing to do in this case is to remove and replace the weather-stripping. This is an easy task and material is inexpensive.

Sometimes the door does not have weather-stripping. If this is the case you can replace it with a metal tubular strip. This strip installs on the door stop/jamb and allows you to adjust the strip a small amount to the door to get a good fit.

Sometimes the door will not have a good fit in the jamb or against the weather stripping. This can be corrected in most cases by adjusting the striker plate to allow the door to close further in the jamb.

When repairing the door don’t forget the sweep. Some doors have them and these can easily be replaced if needed. Others will need on installed. This is a simple process and there are a wide variety of them. The most common can be seen above in the diagram. One of the most efficient but difficult to install is the spring loaded. These are hard to locate and require some expertise to install.


Like doors windows tend to leak at the joints. If you have old single pain windows with individual lites you will probably want to consider having them re-glazed and a storm window if they are leaky. The storm window will also help with the energy efficiency of the window and they typically have a better payback than replacement.

The first step with windows is to ensure that you have a tight fit against the top and bottom jambs. Weather-stripping is easily installed and there is a variety of types. You can use a peal and stick foam or a tack on metal strip. If you are using the peal and stick make sure you have a clean surface before applying.

If you have a leak in the middle between the two windows you can again use a peal and stick or tack on depending on the window. Your clearance will be less than the top and bottom so the weather-stripping cannot be as thick.

Finally for the sides, your fix for this will depend on the manufacture. For older windows you may have to use a spring metal. If you have older style windows that still have weights you can get covers for the holes where the ropes go through. For newer windows it may simply be a leak in the track and manufacturers have caps that can stop these leaks.

Also don’t forget to make sure your lock is in good shape and closing tight on your window. Your lock can help keep the window sealed at the top and bottom.

Use Solar Powered Lights

Most of your landscape lighting is used for accent lighting or safety. You can commonly find these lights powered by photovoltaics in your local home stores. The lights work well in areas that receive sunlight and can cut your electrical cost. They also are easy to install and don’t require any wiring.