A great HVAC (Heating, Ventilation, Air Conditioning) system is one of the few investments that can pay you back over time. These mechanical systems are at the heart of an efficient and healthy home. Meadowlark installs the best mechanical systems available. We constantly work to improve efficiency and operation of the systems we install in our homes. From computer-aided ductwork design, to expert geothermal heating and cooling installations, to state of the art passive techniques, we’ll help figure out the right system for your home. You can reap the benefits of a home that is comfortable, healthy and energy-efficient.
High Performance Heating and Cooling
The cheapest way to save money on mechanical system operation expenses is to upgrade aging equipment with newer, more energy-efficient equipment. One way to gauge the efficiency of equipment is to look at it’s AFUE rating. That stands for the difference between rated and actual input. Aging, inefficient equipment can add as much as 30% to the costs of heating and cooling your house and can contribute to poor indoor air quality.
If you are installing a new furnace, upgrading to variable-speed modulating equipment is a sound investment. Investing extra dollars in a highly efficient furnace and duct system will pay for itself in just a few years. Likewise, there are many options for more efficient boiler systems. Our systems will operate more efficiently with longer life and enhanced comfort in the home. They are “right-sized” using computer modeling data for the home and for each room.
Keeping your mechanical system clean and operating correctly requires maintenance, just like any other part of your home. Clean burners operate more efficiently. Clean filtration systems make the system operate without strain and keep your interior air quality higher. Save money and breathe better air by installing the best equipment and keeping your system in good operational condition.
Starting about five feet beneath your feet, the earth maintains a constant temperature with nearly infinite energy. In Michigan, that temperature is about 52 degrees Fahrenheit. By using a geothermal heat pump system that taps into the constant temperature of the earth, you can very efficiently heat your house in winter and cool it in summer. The system can also supply a good portion of your hot water for essentially free.
Geothermal heat pumps work exactly like your refrigerator or air conditioning systems. Using the refrigeration cycle, those devices convert a fluid from gas to liquid and back using a compressor and a heat exchanger. This “latent heat of transformation” releases heat energy into a heat sink during the cooling cycle. This heat sink with a standard air conditioning system is the outside air, while a refrigerator’s heat sink is the air in your home.
With a geothermal heat pump, the heat sink is the ground, which is significantly cooler than ambient air. This makes a heat pump very efficient for cooling. Better yet, with a geothermal heat pump, we can run this cycle in reverse, drawing energy from the earth and using the air in a home as a heat sink. This heats a home effectively far more efficiently than standard heating equipment.
A geothermal system uses electricity to run the heat pump, but for every unit of electricity we use, we can capture nearly 4.5 units of heating power and 3.5 units of cooling power. Why the discrepancy between the two? The electrical energy we use to run the system in the home ultimately creates heat, and this works against the system when we are trying to remove heat from the home.
Geothermal earth fields can be run in a variety of methods. Most commonly, fields are either installed as horizontal trenches on the lot or as vertical fields which are drilled into the ground using well-drilling equipment. Horizontal fields are cheaper and more efficient, but require a lot that is big enough to make several trenches that are around 100 feet long. Vertical drilling works well on smaller lots where space is at a premium. Both vertical and horizontal loop systems are closed-loop systems, meaning the fluid that transfers energy re-circulates in the fields.
Geothermal systems can be used for heating with forced air or radiant floor systems. Because the maximum temperature we can achieve with a geothermal system is about 125° Fahrenheit, traditional hot water or steam boiler systems do not work efficiently with these systems
A geothermal system works best when the building envelope is already tight and well-insulated. It is important to view a geothermal system as part of a highly efficient home, not just the end goal. Insulation and air-sealing are much less expensive to install, and the money invested in these items can frequently be offset by a smaller geothermal system that costs less to install.
Because geothermal heating and cooling is so efficient, however, both DTE Energy and the federal government offer incentives to homeowners who use it. DTE Energy gives geothermal energy users a lower electrical rate, bring the cost of the electrical energy closer to the low price of natural gas, and beating the cost of propane handily.
The federal government also offers a 30 percent unlimited tax credit for geothermal systems. With this tax credit, 30 percent of the total cost for all components of a geothermal system and the labor to install them are given back to consumers as a credit directly off their total tax bill. With these incentives, the high upfront cost of geothermal makes sense, particularly if a new furnace is being installed anyway.
An efficient building envelope coupled with geothermal heating and cooling can bring average monthly heating and cooling bills to about $50 or lower. This savings combined with available incentives can make geothermal systems have a reasonable payoff period for the high cost of installation, particularly if you are installing a new heating and cooling system anyway.
Radiant energy is how human beings experience heat. Think of the warm sun on a spring day and imagine how that heat feels. While not as intense a heat source, radiant floors provide a similar experience.
Radiant floors require less energy to heat a home because they simply feel warmer. With a radiant floor, 65 degrees feels as comfortable as an air temperature of 70 degrees, but that incremental difference is significant. As the difference in temperature between outside and inside becomes greater, progressively more energy is required to maintain that indoor temperature. A five-degree difference from 65 to 70 degrees can save more energy than a fifteen-degree difference at a lower temperature.
Interestingly, radiant floors feel less noticeable in a high-performance home because the home holds the heat much better, and the difference between the temperature of the air and the temperature of the floor is more consistent.
Radiant floors are a great option for comfort and energy efficiency. They can be retrofitted into old houses or installed in new houses embedded in lightweight concrete or on specially designed subfloors. While radiant floors can be expensive to install, most homeowners who have them would never go back to forced-air heating.
The EPA has stated that the average US home has worse air quality that the air in our most polluted cites. In fact, the air in the average US home is ranked as the 5th worst environmental hazard! One of the reasons is that while an individual item in our home may not cause a significant health risk, the cumulative effect of the thousands of chemicals we bring into our home, many of them untested, has been shown to be a serious risk. Asthma and allergies have steadily risen to epidemic rates since we first began tightening up houses in the 1970’s. Americans spend more time than ever indoors, exacerbating the problem.
The average home in the United States has many small air leaks that can add up to a total size of an open window sash. The problem is that these leaks are not controlled, and frequently deposit fresh air where we don’t need it, i.e. in basements, crawl spaces and attics. This efficiently strips energy from the house and causes uncomfortable home environments, while not really solving the problem of interior air quality.
There are many things a homeowner can do to improve indoor air quality: introduce less chemicals and manufactured goods into the home, make sure the house has positive air pressure relative to an attached garage, install finished goods with low VOC content, and keep chemicals and cleaning agents out of living areas. A good rule of thumb is that if you can smell something, like a plastic toy, it’s off-gassing into your home.
A homeowner can also mechanically ventilate their home through a ducted system. Using devices like a Heat Recovery Ventilator (HRV) or an Energy Recovery Ventilator (ERV), we can provide an adequate amount of air changes to make a home have healthier air quality, while recovering about 70% of the energy that we already paid to condition from the outgoing air. An ERV also balances water vapor content between the incoming and outgoing air streams, helping dehumidify air in the summer and providing moisture in the air in the winter without a separate humidification system.
Better yet, a ducted ventilation system can take stale air from areas that we want to dehumidify, like bathrooms, or areas that tend to have a bit more air pollution, like utility rooms. We can remove pollutant or moisture laden air from these areas and impart fresh air to the areas of our home where we spend the most time, bedrooms and living areas. It’s a great way to keep the air in our homes healthy while saving energy.
As we tighten up buildings for greater energy performance, it is critical to think of the air quality in that building. Almost all buildings and their occupants could benefit from better, more controlled air exchange. In the case of a tight building, however, it is absolutely imperative for the health of the occupants. We at Meadowlark always say; “If your mechanical contractor doesn’t know much about mechanical ventilation equipment or says you don’t need it, you should find another mechanical contractor.” This equipment is a big part of the the “V” letter in HVAC, and without it, it just spells HAC.
Besides a ventilation system, another component of good indoor air quality is an air purification system, which filters and purifies air through a duct system. You can significantly increase the air quality in your home at a low cost simply by installing a better return air filter system.
One indication of air quality is the minimum efficiency reporting value rating—the MERV rating (Minimum Efficiency Reporting Value)—which measures the effectiveness of air filters on a scale of 1 to 16. A filter rated at 16 will capture more than 95 percent of airborne particles on a single pass through the filter. However, this level of efficiency doesn’t allow air to move freely within the system and actually results in a decrease in the system’s overall efficiency.
A good media filter has a MERV rating of 10, which effectively removes most of the larger dust particles from the air without significantly impeding air flow. An electronic air cleaner can be added to boost the MERV rating to 13, but these use more energy and require regular maintenance to operate well.
High-efficiency particulate absorbing (HEPA) filters with a MERV rating of 16 are also effective air cleaners, but they are usually installed in a separate branch of the duct system. They can impede air flow too much to be added to a normal return air duct system.
In addition to filtering air, you could install a biocide chamber, which uses ultraviolet (UV) light to actively kill bacteria, viruses, and mold spores in the air. These particles still need to be filtered out of the air, but at least they won’t reproduce.
The last variable regarding indoor air quality is the humidity, or moisture content, of the air. A building with about 35 to 40 percent relative humidity will feel comfortable without drying out skin and nasal passages. That level of humidity isn’t high enough to support active mold growth. A building’s humidity can be controlled through mechanical ventilation devices, but whole-house humidifiers and dehumidifiers can also maintain the preferred humidity level in your home.
Proper duct work is one of the most important factors in energy efficiency, health, and comfort in a home. Unfortunately, proper duct work is also one of the most overlooked parts of an efficient mechanical system, and installing it is often considered an entry-level job requiring little experience or training.
Planning duct work, however, is part art and part science, and it should be modeled by computer software to ensure that each room receives the right amount of air supply and return. A duct system should adhere to the same principles as fluid dynamics, that is, radius turns and as few bends and obstructions as possible.
Duct work should also have as few gaps as possible. While all duct work should be properly sealed with either mastic or foil tape, sealed gaps aren’t designed for long-term performance. Joint sealants eventually fail, and properly installed duct work shouldn’t be compromised by the failure of joint sealants.
The placement of cold air returns is another consideration that affects both health and the system’s efficiency. Usually, cold air returns in a duct system are located in the framing openings. The problem is that these areas are impossible to clean, and they become excellent incubators for dust and microbes.
Also, framing chases have gaps and openings, and these suck air into them as well, so using framing chases as cold air returns decreases the efficiency with which air is drawn from the right locations. A properly ducted cold air return helps a system to operate efficiently and to provide better air quality.
Placing duct work in unconditioned spaces should also be avoided. Even if the ducts are insulated, it is usually not at a high R-value, and they will continuously lose energy to the unconditioned area. When duct work must be run in crawl spaces and attics, try bring these areas into the conditioned space. Barring that, build a well-insulated chase around the duct work. This helps those ducts lose less energy and keeps the rooms they serve at a more comfortable temperature.
Two types of hot water heaters are commonly used in homes today: direct vent and power-assisted vent. However, neither is the most efficient way to heat water. Direct-vent heaters use the house’s chimney to passively vent the system. The power-vent hot water heater uses an electric fan to vent through the side wall of a house, and therefore doesn’t require a chimney.
While a power-vent system is slightly more efficient (0.62-0.65 ratio of useful energy to total energy used vs. 0.55-0.62 for a direct-vent system), both systems still lose about 35 to 40 percent of every unit of gas used to heat the water. Also, the system’s storage tanks usually have only about one inch of insulation, so it doesn’t store hot water very well, either.
Even though the upfront cost is low, these standard water heaters can cost several hundred dollars per year to operate and will last about 12 to 15 years. So this is one area where it makes sense to upgrade your hot water heating system.
Two efficient options are available: on-demand (also known as tankless) hot water heaters and heat pump assisted heaters. Widely used in Western Europe, on-demand hot water heaters, as the name implies, heat water only as it is needed in the house rather than storing it in a tank. Thus, because there is no tank, they are sometimes advertised as providing unlimited hot water.
On-demand hot water systems burn gas with about 95 percent efficiency; therefore, they save a lot of energy compared to a traditional tank system. But equipment costs for an on-demand system are high, installation costs are high, yearly maintenance is required to prevent hard water deposits in the copper lines, and there are sometimes long wait times for hot water. Also, if you pay for municipal water, you will probably use more water, thus diluting the benefits of a more efficient system.
Next generation systems are ultra-efficient hot water tank systems. Internal heat exchangers boost the efficiency of a storage tank system to about 95 percent, the same as an on-demand system. While they do continuously heat a tank of water, the insulation value is usually better, so they store that energy more efficiently. Additionally, recovery time is so fast that you could downsize your tank with no noticeable difference in performance. Some tanks are glass-lined, which extends the life of the water heater and requires less maintenance.
There are new hybrid models entering the marketplace. These are on-demand systems with a small 5 or 10 gallon buffer tank attached. This effectively eliminates the performance issues with on-demand systems with less stand-by heat losses from the tank of water. Like traditional on-demand systems, these will need more frequent maintenance.
Tank systems can easily be installed to recirculate hot water. Recirculating hot water lines will lose energy to the home through the pipes, but it can save a lot of water by significantly reducing the amount of water going down the drain waiting for hot water. With a recirculating system, you would rarely have to wait more than 10 seconds for hot water at any fixture.
Recirculating hot water, in addition to being a nice comfort feature, can save thousands of gallons of water per person over the course of a year. Recirculating systems that continuously cycle water will use nearly twice the amount of energy to heat water, thus destroying some of the efficiency of the system. Using a pump timer or temperature control, occupancy sensor or switch in areas of hot water use, or a combination of these techniques, a recirculating line can make your home perform to the best of it’s ability.
A well-designed recirculating hot water system offers the best of all worlds – significantly less energy use to heat water and less than a pint of water wasted to get hot water at the end point of use.
Advanced Building Techniques
One key to an energy efficiency and healthy home is a home with a tight envelope. Meadowlark Builders are experts in Advanced Building Techniques and materials used to create the tightest home envelopes possible. To achieve this we use computer modeling and build with Insulated Concrete Forms (ICFs), Durisol ICFs, Structural Insulated Panels (SIPs), Advanced Framing Techniques (AFTs). As masters of Advanced Building Techniques and materials, Meadowlark Builders has built some of the most energy-efficient homes in the country.
Traditionally, houses are framed in wood. This wood skeleton determines the shape of the house and its structural integrity. Framing a house is usually a pretty straightforward affair, but by applying some new thinking and advanced framing techniques (AFT; also called California framing), Meadowlark Builders has refined a system that reduces the amount of lumber used in the frame and increases the amount of insulation. Our modified AFT creates a sturdy, energy-efficient envelope for less money.
With conventional framing techniques, the exterior walls of a home are composed of about 25 percent lumber. Add a few windows and only about half the exterior wall can be insulated. With AFT, we use about 25 to 30 percent less lumber in the frame, and thus we can place 30 percent more insulation in the walls of a home.
AFT is a method of framing for load paths—lumber is only used where it’s needed. For example, this diagram shows how framing members line up from rafter to the basement rim joist.
These diagrams show how we reduce the wood used in the exterior envelope. Notice the 2-stud, or California, corner. An interior wall buck allows us to insulate an area that is usually a solid block of wood.
Notice also that headers are sized for the load, and even those load-bearing headers use engineered lumber that is stronger and allows insulation to be placed in the wall.
Although these homes are more efficient than their conventionally framed counterparts, we can go one better. By adding two layers of 1-inch rigid polyisocyanurate insulation board (polyiso) on the exterior, we create a thermal barrier between the wood members and the exterior. This forms an excellent air infiltration barrier and also adds an R-10 insulation factor to the total wall assembly.This construction technique rivals structural insulated panels (SIPs) in efficiency, but it costs less. Below are some pictures of this technique in action (this installation uses polystyrene, a product we no longer use due to it’s high carbon footprint):
On the interior of the walls, the rigid polyiso gives us a few more options for insulation. We can safely use cellulose since the dew point is outside between the foam layers, and with staggered seams on the foam board, the air infiltration should be minimal. We can also insulate with open-cell spray foam that won’t shrink or settle and that adds even more air-sealing properties.
Notice how we carefully caulk the frame with the cellulose technique, and that our rim joist between the first and second floor is still insulated with the open-cell foam. This potentially leaky area needs insulation that will stay in place and seal it.
Another benefit of this technique is that we can hold the siding material off of the house with sleepers, also called a Rain Screen. The siding material will last longer and need to be painted less often. This vent will also keep the home cooler in the summer.
We also use this modified technique for roofs. The following picture shows a roof that has the thermal break, an R-15 insulation rating, and a vented cold deck. With spray foam on the underside between the rafters, this roof will be durable and energy efficient. Best of all, ice dams can’t form on this roof in winter, and the roof won’t add heat to the house in the summer.
We like our modified AFT because it’s cost-effective and creates a very tight and energy-efficient house. Other building systems have good points as well, but AFT has earned its place in our bag of tricks.
Traditional masonry foundations do a good job of supporting the structure above them, but they also have some serious limitations. For one thing, they’re a large source of heat loss in a home. A masonry foundation is a nearly infinite heat sink that will absorb any amount of energy you throw at it. Then, if the drainage around the foundation isn’t right, it may also transfer water into the home.
So, at Meadowlark Builders, we’re fans of insulated concrete form (ICF) foundations. ICFs usually consist of a molded expanded polystyrene (EPS) shell that stacks together like Legos to make forms that concrete is then poured into. When these forms are filled with concrete they make a poured masonry wall that is comfortable and dry. This is a picture of an EPS ICF block:
Unlike a traditional uninsulated masonry wall, however, this wall has about an R-25 insulation value. By contrast, the traditional masonry wall has an R-1 value—the same as a single pane of glass. Here’s what R-1 looks like next to R-25 in a thermal image:
You can clearly see that a masonry wall transmits a lot of thermal energy while an ICF house keeps the heat much better.
But why stop at the foundation? ICFs make strong, tight, exterior walls as well. In fact, mid-rise hotels, particularly in hurricane-prone areas, are built of ICFs. For a residential home, ICF walls are energy efficient, quiet on the interior, and extremely durable. How durable? Look at these images of various disasters:
This is an image of a neighborhood where an F-4 tornado came through. The frame houses have become just litter on the landscape, while the ICF house, which was under construction, is ready to continue building.
Last, this is a picture of a car hitting an ICF home at 85 mph. The car is totaled, while the ICF house needs a bit of stucco repair. Don’t try this with a wood-frame structure!
ICFs aren’t without environmental issues, however. For one thing, concrete takes a lot of energy to produce, mostly because 15 percent of concrete is composed of Portland cement. This material is basically a mixture of rocks and minerals—limestone, clay, shale, or sand, for example—that are ground to a powder and heated in a kiln to about 1450 degrees Centigrade.
However, recently fly ash has become a good substitute for Portland cement in concrete. Fly ash is a residue of coal combustion, which used to be released into the atmosphere from inefficient coal-fired plants. Released into natural systems, fly ash is devastating to wildlife and waterways, but it also has cement-like properties. Now, due to more efficient coal combustion, what used to go up the chimney can replace up to 30 percent of the Portland cement used in concrete. In fact, about 40 percent of fly ash produced in the U.S. is recycled into concrete.
Finally, there’s the polystyrene shell of the ICF. Polystyrene is a petroleum by-product, and there are good environmental reasons to avoid these products. Straw bale houses are one alternative, as are Durisol ICFs.
So, while ICFs are expensive to produce and install, they create tight, energy-efficient houses that last a really long time. How long? These are some concrete walls the Romans built:
In short, a building that lasts for centuries—or millennia—probably saves much more energy over its lifespan than the energy that went into constructing it.
Cement fiber ICFs were developed in Europe after World War II. This type of ICF is basically a block of Portland cement impregnated with other materials—ground lumber after World War II or mineral wool, a non-compressible, rot-proof insulation.
Durisol is one brand of cement-fiber block. It’s a natural product and easy to work with. Durisol blocks are also hygroscopic, meaning they absorb excess moisture and release it slowly, providing a more even moisture content in the air. But the best part is that the blocks bias the concrete to the inside of the building. That’s important, because it allows the building to take advantage of the large thermal mass of the concrete.
Most ICFs have the concrete in the middle. They make a great structure, but the polystyrene shell then releases as much stored energy to the outside of the structure as to the inside. That creates a good buffer against interior temperature swings, but it doesn’t capture the inherent energy of the structure.
By biasing the concrete to the inside, Durisol blocks store more of the energy used to heat the house. When paired with south-facing, low-energy windows, the house is heated by the sun during the day, and the excess energy is stored in the concrete blocks, extending the solar effect by many hours. This is the concept of a passive house, which is a home heated nearly exclusively with solar energy.
Meadowlark Builders has developed a special technique to maximize the performance of Durisol Blocks. By wrapping the home with polystyrene board insulation, we provide a thermal break from the outside elements. Then we install siding with a venting system called a Rain Screen. This method creates a very tight exterior wall with an insulation value of R-34; it biases the concrete to the inside, and provides a great buffer for temperature and moisture content of the interior air. Even if the power goes out, the sun alone can keep the home reasonably comfortable in winter and naturally cool in summer. A drainage plane behind the siding and roof also helps cool the building.
We constructed the Phoenix House using this method, and even though we built it in the winter, the interior temperature would get up to 63 degrees during Michigan’s cold February days.
Although Durisol blocks have many advantages, the system is expensive to build with a payoff period of over 20 years. With a southern exposure, however, a house can be heated and cooled with very little energy or maintenance. A Durisol ICF foundation has to be viewed as a long-term investment both in the environment and in a durable, energy-efficient structure.
Fiber cement ICFs were developed in Europe after World War II. This type of ICF consists of ground up post-consumer wood waste, portland cement and a non-compressible rot-proof insulation material such as mineral wool. This is a picture of a fiber cement ICF block:
Durisol is one brand of cement-fiber block, pictured above. It’s a natural product that’s easy to work with. Durisol blocks are also hygroscopic, meaning they absorb excess moisture and release it slowly, providing a more even moisture content in the air. But the best part is that the blocks bias the concrete to the inside of the building. That’s important, because it allows the building to take advantage of the large thermal mass of the concrete.
Most ICFs have the concrete in the middle. They make a great structure, but the polystyrene shell then releases as much stored energy to the outside of the structure as to the inside. That creates a good buffer against interior temperature swings, but it doesn’t capture the inherent energy of the structure.
By biasing the concrete to the inside, Durisol blocks store more of the energy used to heat the house. When paired with south-facing, low-energy windows, the house is heated by the sun during the day, and the excess energy is stored in the concrete blocks, extending the solar effect by many hours. This can be an effective technique for building a passive house.
Meadowlark Builders has developed a special technique to maximize the performance of Durisol Blocks. By wrapping the home with polyisocyanurate board insulation, we provide a thermal break from the outside elements. Then we install siding with a venting system called a Rain Screen.
This method creates a very tight exterior wall with an insulation value of R-34; it biases the concrete to the inside, and provides a great buffer for temperature and moisture content of the interior air. Even if the power goes out, the sun alone can keep the home reasonably comfortable in winter and naturally cool in summer. A drainage plane behind the siding and roof also helps cool the building.
Structural insulated panels (SIPs) are a building material that sandwiches a thick polystyrene foam between two rigid boards (oriented strand board, or OSB). This creates a strong, lightweight, and very energy-efficient product that essentially combines the framing material with the insulation. This eliminates the thermal gap between the exterior and interior wood frame and creates a very tight envelope with a high R-value rating.
SIPs can be be used for most structural parts of a home’s envelope—roof, walls, and even floors. They go up fast—a good crew with a good plan can frame all the exterior walls of one floor of an average-sized house in a day. The panels are strong, too—up to three times stronger than a conventional framed house.
An Italianate Dream SIP Walls
An Italianate Dream SIP Walls and Roof
An Italianate Dream SIP Finished
While SIPs are typically used for new builds, they can also be a good technique for a remodel as well. Due to their structural rigidity, and their ability to be used as floors, walls, or roof planes, SIPs can make an exceptionally air-tight wing on a house that acts as a unit. SIPs also create very rigid and energy-efficient floors, which make them a cost-effective choice for a quality addition without a continuous foundation. Here are some photos of SIPs being used in remodeling situation
First Floor SIP Addition
Second Floor SIP Addition
SIP Floor and SIP Walls
SIP Addition Before Roof
Setting a Roof Panel
Finished SIP Addition
When SIPs are used as roof structures, the roof then becomes part of the insulated envelope, and the attic becomes living space. That can have a big impact on usable square footage for a home, adding up to 3/4 of the total footprint of the house in conditioned bonus space. Best of all, as soon as the windows and doors are installed, the house is already insulated and ready to hold the heat, better than most houses. That can make a big difference for cold-weather construction.
First Roof Panel
Last Roof Panel
The Finished Attic Space
Overall, while more expensive, SIPs do have some advantages over frame construction. They are highly energy efficient structures with greater structural rigidity. The have been in use for over 70 years, and can make a long-lasting home that will be very comfortable. Where budget allows, this can be an excellent technique to consider, and in some situations, this can even be the most cost-effective way to proceed.
Modular units and pre-fabricated panels can be a fast and efficient way to erect a house. Because these are built in to factory standards and made to easily withstand shipping to the site, these buildings tend to be very well constructed, and can be made to be energy efficient.
Modular homes can be configured within a rectangle up to 16 feet in width by up to 60 feet in length. Within that rectangle, partition walls can be any configuration. They can be butted together with thick “Marriage Walls” where there are openings to other modules. The modules can also be stacked to allow for second stories.
The experience of living in a modular home is that same as any other home. With customized finishes, the modules weave together seamlessly. Our testing shows us that modular homes can be made nearly as tight as other houses. With an energy-efficient foundation, good weatherization techniques, and a geothermal heating and cooling system, these homes can be real energy champs.
Modular homes typically come with the lowest-priced fixtures and finishes that can be applied, which is why they can be very inexpensive. Upgrading to our custom energy package, available only through Meadowlark Builders, adds a significant amount to the price tag, but pays for itself in a reasonable time period. Other custom finishes will add to the price as well, but those finishes will tend to look better and last longer.
Modular homes are an attractive option that will save a decent sum of money in construction relative to a custom-built home. They are not useful in every case, but they can be a versatile tool to use when you have an open palette and a tight budget. In some cases, they might be nearly the floorplan you were thinking of anyway.
Did you know that a house in Michigan can heat and cool itself without a furnace or an air conditioner? By using the sun, the earth, and prevailing summer breezes, we can heat and cool a house using nothing but passive energy flow.
The standards for passive houses were developed in Germany by the PassivHaus Institute. Inspired by passive house in Saskatchewan and another in California that were built after our first energy crisis in the mid-1970’s, Dr. Wolfgang Feist, a German physicist, founded the Institute in 1996.
Passive Houses meet incredibly rigorous requirements for their air infiltration rates, insulation, and total energy use. In fact, a 2000 square foot house can only use 22,200 kilowatt-hours per year. That is equivalent of twenty-five 100-watt lightbulbs being on in a year, and covers all heating and cooling, and all electrical loads. That is without using solar panels, and without using a geothermal heating system, only passive methods.
If you can do it in Germany or Saskatchewan, you can do it in Michigan. Passive houses will have very high R-value walls and roofs, be incredibly airtight, and have “super windows,” efficient windows with a U-value of 0.14 or lower. As tight as a Styrofoam cooler, they must have active heat recovery ventilation (a source of electrical use and some heat loss that will cost many of those light bulbs).
PASSIVE SOLAR ENERGY AND THERMAL MASS
Passive houses rely on the sun for winter heating, and will work better if there is a lot of thermal mass in the house. The thermal mass stores excess energy and radiates it at night, when heating loads begin to climb again. Trombe walls, shown in these diagrams, can help store solar energy and cause thermal currents to distribute it within the house:
Trombe Wall Day
Trombe Wall Night
Interior Trombe walls can be painted black on the window side to absorb maximum solar energy. The sun can also shine on a dark-colored concrete floor or an interior concrete wall for greater energy gain. Any thermal mass on the inside of the home, however, will help to store and modulate heat content.
Houses can also benefit from thermal mass without Trombe walls. If the sun can shine on floor and wall surfaces with mass, these too will absorb that energy and release it slowly after the sun goes down.
Direct Gain Day
Direct Gain Night
It is important to note that windows must be shaded in the summertime. A Passive house can overheat if too much sun enters the building when the ambient temperature outside is warm. We must keep the sun’s rays from entering the house in warm weather.
Thermal mass can have a strong benefit in the summertime. By designing the house to capture prevailing summer breezes, and an outlet on the high leeward side of the building, we can suck hot air out of the house in the late afternoon and cool the structure of the house with cool nighttime air. The thermal mass of the house can store the cool of the nighttime air and keep the house cool if the windows are closed during a hot day.
ENERGY EFFICIENT WINDOW
When you build a very efficient thermal envelope, normal windows jump from being about 20% of the total heat loss to somewhere around 50% of the total heat loss. Through the use of advanced windows, we can bring that back down in proportion with the low energy use of the home.
These windows must seal well and have an insulated frame as part of the assembly. They can also be triple or quadruple-paned with xenon gas instead of argon gas between the panes. Xenon is a larger inert gas molecule than argon, it will distribute itself in the pane better and will not leak out of the frame nearly as easily as argon.
The glass itself will have high-performance coatings as well. These coatings are tuned to the orientation of the window. Typically we want south-facing windows that let the Sun, and it’s energy, shine on in. East and west windows should reflect the sun’s energy so that we don’t overheat the house in the summertime. East, west and north windows, and those under porches, should keep as much heat in the home as possible.
A typical low-e, argon filled window manufactured in the United States will have a U-factor of about U-0.32. U-value is the reciprocal of R-value, so U-0.32 equals R-3.1. That is the R-value of the entire window assembly, not just the middle of the pane of glass, which can be greater. That’s not a lot of insulation in the part of the wall with a window, and that’s why windows can feel cold to stand next to in the winter.
High-performance windows start at about U-0.15 and can go much lower. That’s starting at an R-value of 6.7 and go up to R-21 (U-0.045). It’s a remarkable improvement, but does come at a cost. When the rest of your house’s envelope is high-performance, however, these windows can make a lot of sense.
In a home that is tight and stores energy well, particularly a passive solar house, tempering our incoming air can help make a big jump in efficiency of the home. There is a perfect place to do that, and we are probably digging in there anyway to construct the home. The earth maintains a steady temperature of about 52° year round at about five feet below the surface. The same principle that makes the earth a good heat sink for geothermal heating and cooling can help us condition the air that is coming into the house.
A perforated and filtered drain tile tube that is placed at least five feet underground and has well-drained soil underneath it, can be a path that incoming air can take before entering the house. Since the difference in temperature outside and the temperature of the ground may be quite large, we need a long obstructed path for the incoming air to travel.
This typically means a serpentine pattern for several hundred feet underground (perhaps going around the house) will create enough opportunity to exchange temperature and moisture in the ground. In the summer, we will cool and dehumidify the air, as its dew point will be reached in the cool of the earth. In the winter, we are pre-heating the air and adding moisture content.
We can make this intake go directly into our Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV), and the difference between the incoming and outgoing air will be much smaller. That means we will use a lot less energy to bring the incoming air up to temperature with the ambient temperature in the house, and can have lots of fresh air in our tight and well-insulated house.
It is important to make sure that the earth tubes are well drained with no standing water, and that the drain tile has a filter sock with peastone and another filter cloth layer above it. Care must be taken to avoid making an assembly where bacteria and mold will thrive, thus introducing unwanted microorganisms into the house. These assemblies can work great and can be an important strategy for a Passive House.
DURISOL ICFS AND PASSIVE HOUSES
Gaining this interior thermal mass is one reason we like Durisol ICFs, particularly our modified version, which provides a high R-value wall. These passive house methods are what we used to build The Phoenix House. This house will heat up to 63° during the day when it is below freezing outside, and hold it’s temperature for several hours after the sun goes down. Although this house will not achieve “Passive House” status, it is a home that is very close to net-zero energy with the addition of solar panels.
Advanced Water Systems
Water and energy are inextricably linked. Energy production is one of our nation’s largest consumers of water, and moving and purifying water consumes lots of energy. But water is also a precious resource, far more so than energy. You can live for 5 days without electricity, but try doing that with water.
About 1% of the world’s water is fresh and potable and in Michigan, we are surrounded by 20% of the world’s potable water supply. It is a resource that we all cherish, and water protection and conservation is more important than ever. Even in Michigan, we are over-taxing our aquifers and wasting water at an enormous rate. Many of the techniques below exist to build homes that use far less water with no decrease in performance. These techniques can also save a lot on your monthly water bill.
In most cases there is no right answer for every house or building. Most building materials and methods have pluses and minuses, and water supply line materials are no exception. Regions of our country have different climates, soil conditions, and water chemistry. The goal in all cases is to find is to find what is right for your home in your location.
Copper is a durable soft metal and has the following advantages:
- It can be installed relatively quickly due to its high volume of usage.
- Copper is also bacteriostatic, meaning that bacteria won’t grow in the pipes.
- Copper pipes are resistant to corrosion under most conditions and won’t rust or degrade in the elements.
- Chlorine, Fluorine and other contents of water don’t react with copper.
- If your water has sufficient (but not too much) mineral content, you can effectively line the piping with a mineral layer that keeps water quality high.
- It is fully recyclable.
But copper also has some serious disadvantages, namely:
- Copper piping has little tensile strength, and can therefore burst easily if water freezes in it.
- If your water is acidic, it will corrode the copper piping over time. This causes a few problems:
- The copper ions that are in the water are a health hazard to you and your family.
- Copper ions are extremely toxic to aquatic life, acting much like mercury does for humans, and the copper ions can end up in our rivers and lakes.
- This thins the copper walls over time, making the pipes likely to burst after 30 years or so.
- Copper mining causes terrible environmental damage in several areas of the world.
- The raw material is expensive, and prone to large price fluctuations.
- Copper is harder to plumb with a water-saving manifold system.
- Hard water can cause mineral build-up in copper lines that will restrict water flow over time.
- Water does not flow smoothly in copper pipes, causing more water use.
- Pipes can “hammer” by sudden water stoppage
- Copper is thermally conductive, and can lose heat quickly from the pipe.
PEX stands for cross-linked polyethylene. It is a type of plastic tubing made from high-density polyethylene. It is used for radiant floor heat tubing and for water supply. PEX has a lot of advantages over copper piping, such as:
- It is far less expensive as a raw material.
- It has a much lower carbon footprint.
- It is completely resistant to acids.
- It does not allow mineral scaling to build up.
- Creates far less water turbulence inside, and therefore less water provides equivalent performance.
- It is very tough to damage mechanically and doesn’t break down over time.
- It is an ideal piping for a water-saving manifold system.
- Does not cause “hammering” when water is shut off
- PEX is not as thermally conductive, so hot water stays in the pipe longer
But PEX does have a few disadvantages as well:
- It degrades rapidly when exposed to ultraviolet light
- It is not recyclable.
- It can react with chlorinated water to make toxic chemicals at extremely low levels.
- Plumbers may charge more for installing it due to unfamiliarity with the product.
So which is right for your home? It depends on where you live. Testing your water can be a good idea. As a rule of thumb, if your water has a pH below 6.5, definitely don’t install copper. Beyond that merits a discussion of your goals for your home.
A traditional plumbing system uses a ¾ inch diameter pipe (or even larger for big homes) that makes a circuit around the house with smaller diameter ½ inch pipes coming off to supply individual fixtures. For hot water supply, this is an extremely inefficient use of water. A larger diameter pipe takes more than twice the amount of hot water to supply a remote fixture than an equivalent ½ inch pipe.
As our homes have become larger with more bathrooms and longer plumbing runs, this makes the problem far greater. Coupled with the inefficient water heating systems that are the standard in most homes, the result is an energy and water equation that is working against the homeowner. Water pipes running in marginally conditioned or unconditioned areas also exacerbate this condition.
Manifold Systems mitigate this this by using ½ inch take-offs very close to the hot water supply. The individual ½ inch runs use a lot less water and save quite a bit of energy because the user is not having to clear out a ¾ inch line before hot water reaches the fixtures.
When you add in the water saving nature of PEX tubing, this becomes an even bigger factor. PEX tubing works great with a manifold system, and red and blue colored PEX can be used to signify hot or cold water. PEX tubing can also be bundled as the lines snake through the house. Here are some pictures of a manifold and tubing:
What’s outside of your house has a great deal of impact on the “green-ness” of your home as well. Aside from location considerations (walkable cities reduce infrastructure and automobile energy use), the lot can also have a big impact.
On any given lot, we want to keep the water that falls on the lot there, and preferably harvest it for use in irrigation. Reducing impervious surfaces that direct water off the lot is a goal. Using native, non-invasive plants is another goal – they will be right for this climate and do not require irrigation. Finally, providing habitat or movement corridors for wildlife on larger lots can also enhance the local environment.
The end result is a yard that will look nice and create a good local environment. If this is combined with an ultra-efficient home with good product choices, we can build in a sustainable fashion that enhances the local ecology.
Pavers, whether used for driveways, sidewalks or patios, are a great-looking way to create a hardscape that will allow water to pass through. While significantly more expensive than concrete or asphalt, they also can have a more attractive appearance. Allowing our hardscapes to drain water through them also allows us to keep water from running places where it’s not wanted – streets, storm drains, and ultimately rivers.
Pavements carry sediments and runoff that can be harmful to an aquatic environment. It is better in all cases to allow water to percolate through, and be purified by, the soil. Many storm water systems are overwhelmed during rain events as infrastructure costs have not kept pace as development has intensified. Permeable pavers are one way to keep more water on the site as density increases.
One of the biggest causes of storm water runoff is a lack of a method to contain the volume of water on-site during a rain event. Storage vessels can help solve that problem. These can range from simple rain barrels at each downspout to full underground cisterns and everything in between.
These are not novel concepts – before the advent of running water, most homes had cisterns to collect rainwater. In fact, adding onto turn-of-the-century buildings almost always includes removing a cistern right behind the house.
Rainwater was once considered essential to harvest, and it is gratifying to see a renewed interest in this type of self-sustainability. This water can also be used for irrigation outside, reducing the amount of tap water used to nourish plants. And since water and energy are so inextricably linked, this also saves resources and money.
It is important to note that water collected from asphalt shingled roofs should not be used for edible gardens. There are trace quantities of heavy metals in the asphalt shingles which could build up over time in the soil and be absorbed into your food. If you want to use the roof runoff for more than ornamental irrigation, a metal roof would be the better choice.
Your non-edible gardens will love the rainwater from even an asphalt roof however, and your local storm water system will thank you.
Xeriscaping is landscaping using methods that reduce or eliminate the need for irrigation. This typically means native plants that are tolerant of the wide range of temperature extremes, and drought-resistant in our area.
A xeriscaped lawn need not be uninteresting or have a lack of color. There are hundreds of ornamental non-invasive plants that like our climate just fine. These plants will likely support the local fauna better, and ultimately be easier on your pocketbook through less water use and landscape maintenance. And because they will spread to find their own balance with each other, weeding will be unnecessary in just a few years.
During WWII, Americans were urged to plant a “Victory Garden”. This worked well to reduce the individual food requirements of the American family, so more food could go to the war effort. These days, food has never been cheaper as a percentage of our budget.
Still many people would like to be closer to the source of their food. As food has become more processed and it’s production more mechanized, many people are beginning to realize that food grown in neither tastes as good or is nearly as healthy. It uses a tremendous amount of energy and is not sustainable for the long term. It is also heavily subsidized by taxpayers and tends to make us more unhealthy.
These days, the situation is not as obvious as a world war, but the consequences are just as profound. As much as our current energy use is on an unsustainable trajectory, our food production systems can be a blight on our beautiful land when profit is the only motive.
A Victory Garden for the 21st century can be a way to learn about food production and enjoy the unbeatable taste of fresh fruits and vegetables. These can be beautiful landscapes that provide little treasures throughout the growing season.