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Welcome to my website. I will be posting articles here periodically about items I hope will be of interest, and to announce what’s happening at the office. Thanks for visiting.

Ron

This is the beginning of a series of articles describing the design decisions and details of an energy efficient single family home for the Chicagoland area. The end result will be a set of specifications or a recipe of the elements required to create a house that will conserve natural resources and save you money. That, to me, is a win win situation.

Am I a tree hugger? Do I put on green jeans every morning? Maybe. Here”s a thought I have often had. Perhaps you”ve had it too. Have you noticed that planet Earth is but a small spec of dust floating in a vast Universe? And only on this little rock called Earth, in all of the zillions of miles of space surrounding us, does there exist life capable of supporting us humans. What are we going to do if we turn our home floating in space into a noxious, toxic wasteland? Move to Mars? Mars is a dead lifeless rock. We have to be responsible stewards of our planet. Is it responsible to consume our natural resources as fast as we possibly can and spew pollution all over the land, sea and air? All the talk about “sustainable” or “green” design seems like common sense to me. Would you rather live in paradise or Mars?

OK, so there”s my rant about the environment. What I can more directly see that shocks me are my monthly utility bills. Wouldn”t it be nice to to utililize construction materials and methods that will reduce my costs and reliance on the utility companies? I sure think so.

I would like to close this article with a quote from David Johnston and Scott Gibson, who are co-authors of several excellent books on sustainable building. “What we alternately call green building or sustainable building is a way for people to make a positive difference in the world around them-if not reversing, then at least reducing the impact of humankind on the planet. Not coincidentally, it has its own practical rewards on a scale that all of us can immediately understand. If becoming model citizens of Planet Earth is too much to get our arms around, living in healthier, more comfortable houses that are less expensive to operate and last longer is certainly an attractive idea. Who wouldn”t want to participate in something like that?”

In the next article I will be going over the general planning considerations leading to the design of the house.

Ron

Perhaps you have been thinking about creating an energy efficient house. Maybe you would like to take advantage of everlasting, sustainable energy sources such as wind, solar and geothermal. And maybe you would like to reduce your energy bills and the impact on the environment. Where do you begin? What are the general planning guidelines to set the design specifications for the house?

One consideration is what level of energy savings do you want to achieve? Do you want to be fully independent of the utility companies? This level is termed Net Zero. The house is capable of attaining all the heating, cooling, electrical, water and sewage disposal through its building systems. This can be achieved by a combination of super insulating and air sealing the building envelope, utilization of passive solar design, solar hot water heating, solar electrical generation through photovoltaic panels, potential use of a geothermal heating and cooling system, a well pump for domestic water, rainwater harvesting, a septic field for the sanitary sewer, to name some of the possible solutions.

Some of the systems, such as the well and septic system may only be applicable to a green field site in a rural setting. The cost of some of the systems, such as the photovoltaic system or the geothermal system may not have a good lifecycle cost payback at the present time. Evaluating the pros and cons and the sustainability of each application can provide the basis for selecting various sustainability approaches.

Another consideration is whether you want to achieve carbon neutrality. This looks at the carbon emission that is created in every step of the building and operation of the house, and how that can be reduced. For example, how far did the materials used in the house have to be transported to your site? Longer creates more carbon output. Or how much energy was required to produce a material or resource? Production of cement, for example, produces a lot of carbon emission. From a sustainability standpoint, these factors may guide the choice of materials and systems.

The size of the house is a factor since the greater the square footage, the greater the energy required to heat and cool the house. Close proximity to your workplace and the availability of mass transportation is also desirable to reduce the use of fossil fuels.

For some, health concerns are an issue, especially regarding indoor air quality. In this case the choice of materials that minimize the release of volatile organic compounds and the use of air cleaning and filtration systems to reduce allergens are important considerations.

Another up front consideration is whether to pursue certification from one of the “green” rating agencies. You may have heard of various certification levels such as LEED silver or gold. Certification provides a means of verification that the house is built to a defined level of energy efficient performance and measurement of the house’s energy systems performance. It is important to be able to measure how much energy the house is using to verify you are saving energy and are getting a return on your investment in sustainable building systems. You may also want to know if you are reducing your carbon footprint.

The primary rating agencies are the local building department by the way of the building code requirements, The NAHB (National Association of Homebuilders) National Green Building Standard, the US EPA (Environmental Protection Agency) Energy Star Standards, and the US Green Building Council LEED (Leadership in Energy and Environmental Design) for Homes. The building department requirements are mandatory. The others are voluntary, and the level to be achieved is determined by the client. To attain formal written certification, the design and construction process is monitored and certified by the chosen rating agency. It requires a fee and series of submittals by the building team, and inspections by independent third party raters.

As you can see, deciding how green to go involves a number of choices. There are specific requirements which must be met and various options from which to choose. Determining the most appropriate desired outcome, especially regarding something as personal as your house, will require a weighing of the rational with the emotional considerations each choice presents.

In upcoming articles I will present options for various systems in a house I am designing in the Chicago area. I will go over the available options and outline the reasons I recommend a particular selection.

Ron

The first consideration in designing an energy efficient house is determining the location of the house on the site so that it can benefit from passive solar design. Passive solar design involves the control of solar energy to heat homes in the winter and keep them cooler in the summer. The goal is to reduce or eliminate the use of mechanical means of heating and cooling, such as forced air furnaces, boilers or air conditioning

In the northern hemisphere, the south facing exposure receives the most solar exposure. It can be advantageous to face the long axis of the house southward to get more sunlight. Also, plan enough south facing roof area to accommodate solar collectors. South facing windows need to be designed to allow the optimum amount of sunlight into a space in the winter and keep it out in the summer. A rule of thumb is that in a well insulated exterior wall, the area of the windows should be about 8 to 12 percent of the floor area of the south facing rooms. Too much glass can equal too much heat in the summer.

Two ways of providing summer shade are with fixed overhangs and landscaping. Architectural elements to shade the windows are usually the best option. The shading devices should be sized so that at noon on the winter solstice (Dec. 21), full sun is allowed into the window. On the summer solstice (June 21), the opposite is true, windows should be fully shaded. East and west facing windows should also be shaded from summer sun. For landscaping, deciduous trees which drop their leaves in the winter can provide shade in the summer and allow sunlight in the house in winter. Evergreens on the north exposure can provide a wind block from winter winds.

Determining how much window area can be included in south facing walls also depends on the mass of surfaces directly and indirectly illuminated by sunlight. The higher the volume of mass, the more window area can be placed on the south wall. This is because a higher volume of mass will absorb more heat from the sun and then release it slowly after the sun has gone down. Less volume heats up quickly and then just radiates heat into a space. So for example if a 1 inch thick pine floor is replaced by a 4 inch concrete slab, 50 sq. ft. of glass can be increased to 250 sq. ft.

Placing rooms appropriately to track the sun can take advantage of daylight, which reduces the need for electric lighting. Principal spaces used during the day such as the kitchen and family room would benefit from this, while spaces used less during the day such as bedrooms and bathrooms could be placed on the north side of the house.

Another site consideration is the prevailing wind pattern and natural ventilation. Airflow through the house provides both comfort and high indoor air quality. A most basic ventilation characteristic is that warm air rises and cold air falls. Window placement and location of spaces that allow cross ventilation and a vertical path of airflow for warm air to be released are features that often can easily be provided in the plans for the house.

Water management on the site also needs to be planned for. Avoid locating the house on a low spot of the site, and provide for water runoff away from the house. If the house is in an arid climate, conservation and collection of rain water for landscape irrigation might be a goal. And if a septic field is required for sewage disposal, an appropriate location and soil conditions for the leaching field must be found. Also, a well system may be required for potable water where municipal service is not available.

In the next article we’ll examine elements of the building’s exterior envelope.

As we begin detailing the components of an energy efficient house for the Chicagoland area, we need to decide which level of efficiency to design for. This was discussed in the previous article “how green to go”.

The client for the house wants to achieve energy savings while using conventional construction techniques with some new details and materials to improve energy performance. They do not necessarily want to build to the level of net zero. They also want to spend a reasonable amount of money with an eye to achieving a timely payback to their cost investment in their home. Based on this, we have decided to design to the LEED for Homes standards. While acknowledging the value of obtaining formal certification, for this project the client wants to use the standards as a guideline only.

The house itself is fairly compact. It will have a basement of 1,160 sf, first floor of 1,160 sf and a second floor of 1,292 sf, with access to a rooftop deck space. There are 3 bedrooms and 2 baths. The design is contemporary in appearance. In examining the energy efficient features of the house, we will work our way from the outside-in.

We begin with the building envelope, which is the outer layer of the house. It includes the foundation, walls and roof. In order to save energy, the goal is to build an envelope that is as airtight and well insulated as possible so that the conditioned air stays inside the envelope and inclement weather stays outside.

Let’s start with the foundation. For our location, a conventional basement has a concrete foundation wall, footings and floor slab. It is generally common practice not to provide insulation on the concrete wall or under the slab. These areas can be significant sources of heat loss or gain and need to be insulated. The wall also needs to be well drained and sealed to prevent the intrusion of water. To take care of this, use 2” of closed cell extruded polystyrene rigid insulation board on the exterior of the wall placed over a fluid applied waterproofing membrane (not just the typical asphaltic damproofing). For the interior finish wall, use 1” of rigid insulation applied to the concrete wall. Over this use a 2×4 stud wall with a pressure treated sill plate and fiberglass batt insulation, finished with 5/8” drywall. The underside of the slab should also be insulated, especially when using radiant floor heat in the slab, with 1 1/2” rigid insulation, placed over a polyethelene vapor barrier over a 4” gravel base. The slab is reinforced with wire mesh or fibermesh mix.

To remove water around the foundation, a perimeter drain line wrapped with geotextile fabric and covered by gravel must be placed on the exterior and interior of the footing. Window well drains are also connected to the line. This line is connected to a sump pump which discharges water away from the building.

Regarding the concrete material itself, the production of the cement in the concrete requires a lot of energy, which has an environmental impact. Substituting fly ash, a power plant by product, for some of the cement has been shown to improve the strength of concrete and also recycles an industrial waste product. Typically, 15 % fly ash is added to the mix. Finally, to provide a finished appearance to the rigid insulation, an exterior insulation finish coating which looks like stucco is applied over the exposed insulation.

The insulation R values for the systems are R-29 for the wall (3 inches of extruded polystyrene at R-5 per inch equals R-15 plus R-13 fiberglass batt plus about R-1 for a 10” concrete wall. The floor is R-7.5 (1 1/2 inch of extruded polystyrene). As you can see, this is a significant increase over concrete alone.

In the next article I’ll go over the exterior framing system.

Above the foundation wall, the framing system consists of the walls, floors and roof of the house. There are many different materials, techniques, traditions and cost factors that can determine which systems to use. Wood framing is the most conventional system for single family residential construction in the US. In most urban areas where fire resistance is a concern, exterior walls are often masonry bearing wall systems. Both of these systems are often under insulated and have many air leaks allowing outside air and thermal infiltration. A primary goal of energy efficient construction is to increase insulation and decrease air leakage.

New framing systems to address energy efficiency and sustainability have been developed. Some of these are structural insulated panels (SIP) and insulated concrete forms. Wood framing is still the most prevalent and we will focus on enhancements to this system for the house.

One way to achieve greater efficiency for the exterior wall framing is to utilize techniques developed by the National Association of Home Builders during the 1970’s energy crisis. It is called Optimal Value Engineering or Advanced Framing. It eliminates framing members that serve no structural purpose and makes more room for more insulation. We will also use engineered lumber, which are manufactured framing members which use wood fiber more efficiently than solid sawn lumber. These products are used mainly for the floor and roof framing. Products for the walls are also available but generally are not cost effective compared to sawn lumber.

To avoid thermal bridging of the studs, the exterior of the house is wrapped with one inch of rigid extruded polystyrene insulation. To reduce air infiltration, the use of an outside air barrier wall wrap, with all seams taped and sealed is used. All joints in the framing need to be sealed, especially at the window openings. The inside face of the wall sheathing and underside of the roof sheathing is insulated with 2” of spray polyurethane foam which provides a highly effective air leak seal and high insulation value. The rest of the cavity is filled with fiberglass batt insulation.

So the framing system, from the outside in, looks like this: fiber cement siding or stucco applied over an air barrier over 1” rigid insulation with drainage channels over a secondary air & moisture barrier over ½” plywood sheathing attached to 2×6 wood studs spaced at 24” on center. Floors and roof will utilize engineered truss joists.

The insulation R values are R-32 for the wall (1” of extruded polystyrene at R-5 per inch, plus 2” of spray polyurethane foam at R-6 per inch, plus 3 ½” fiberglass batts at R-15). The roof is R-50 (2” of spray polyurethane foam at R-6 per inch, plus 12” R-38 fiberglass batts).

The attic and roof require careful design because it is the part of the house that is in extreme contact with the outside elements. All the parts of the system need to work together to prevent moisture problems. It starts at the drywall ceiling on the top floor and ends at the roofing material. The roofing keeps water out of the building and the attic space buffers indoor temperatures from the outside temperature. The attic also provides space for thermal insulation, typically between and over the ceiling joists. Attic ventilation evacuates moisture out of the enclosed space.

Planning the attic as a unified system presents new design parameters, especially if ducts are run in the attic. The first step is to define where the air barrier is placed. In typical installations, it is in the ceiling of the space below the attic. To prevent intrusion of moisture from the house, it must be continually unbroken. This is hard to do when vents, lights, doors and other penetrations perforate the air barrier. If air leakage is coming through the barrier, moisture can get into the insulation or even condense on the underside of the roof sheathing during cold temperatures, causing potential mold problems.

Often, ductwork is placed in the unconditioned attic. This is not very good from an energy efficiency standpoint. The ductwork must be insulated, but it is usually only about an R-6 value. The coldest air flows through ducts in the hottest space in the summer and vice versa in the winter.

The condition of air barrier leakage and poor insulation suggests an alternative insulation method for the attic by making it semi conditioned. This is accomplished by putting the air barrier and insulation on the underside of the roof sheathing. This in effect extends the wall insulation value from the roof eave line up to the ridge line. An effective way to do this is to use closed cell urethane spray foam insulation. The foam provides an air seal at the rafter level, and it reduces the temperature of the attic space in the summer, providing a better place to run ductwork. It also keeps any leaked warm interior air from melting snow on the roof during freezing winter temperature, a cause of ice dams. Additionally it provides required insulation for habitable attic space.

With a closed attic, some inside ventilation is required. With a forced air or heat recovery ventilation system, a small supply register is provided in the attic with a return at the opposite end to provide air flow to keep the attic dry. When providing habitable attic space, avoid creating closed off areas where moist air cannot be vented away. When the soffits are sealed from the attic ventilation system, the soffit should have a continuous vent, or the rafter ends and sheathing can be left exposed to the elements to allow drying.

Roofing materials include a wide range of manufactured and natural products. These include wood, slate, tile, metal, single ply membranes and asphalt shingles. From a sustainability standpoint, roofing should have a long service life with minimal maintenance. Our subject house will have a low slope roof with a single ply membrane.

Windows and doors provide our views and openings to the outside. Their appearance and placement are a large part of what gives a house its look, be it large expanses of glass or smaller panes divided by muntins. They also have a significant impact on energy efficiency. Poorly insulated, leaky windows and doors can let in a lot of heat or cold.

Window technology has been constantly improving. Like insulation, they are rated for their ability to resist the flow of heat. Where insulation is rated by R-value, windows use the U value, which is the inverse of an R-value (U=1/R). This means the lower the U-value number, the more energy efficient the window. Plain glass has an R-value of 1, but it is now possible to get super glass assemblies rating at U-0.05, which is equivalent to an R-20 wall.

There are three main factors in a window’s energy performance: frame construction, glass and the spacer material between individual panes of glass. Window frames are typically made of wood, wood with aluminum or vinyl exterior cladding, all vinyl, fiberglass, aluminum and stainless steel. Wood frames are high quality but relatively expensive. They can be susceptible to decay from harsh weather. This can be reduced with exterior cladding material. Vinyl frames are less expensive than wood and are weather resistant. They are prone to expansion and contraction in the heat and cold and can leak air if the weatherstripping seal separates. Fiberglass frames are weather resistant and expand and contract less than vinyl. Both can be filled with urethane foam to lower the U value. Aluminum and stainless steel frames are weather resistant, strong and can accommodate large panes of glass. Their downside is high thermal conductivity which allows significant heat loss, even when they are equipped with a thermal break.

Glass, or glazing, is where most of the technological advance in window design has occurred. Single pane glazing, with an R-1 value used to be the norm. R-1 is about the same as having an open hole in the wall. Windows now have double or triple glazing with an insulating air space between the glass. The air space is filled with argon and/or krypton gas to reduce convection. The glass also can be coated with a low emissive, or low-e coating which reflects infrared energy back toward the warm side of the glass. These features all reduce the U-value of the glazing.

All of this will be of little benefit if the window assembly leaks air or water. Fixed windows, those that don’t open, have the lowest leakage rates. Operable windows, such as awning and casement types have a closure mechanism that pulls the sash frame against a compression gasket, reducing air leaks. When the window is installed, the space between the window frame and rough opening should be caulked or filled with polyurethane foam to eliminate outside air leaks and energy loss. On the exterior of the wall, use a self adhering flashing to seal the window opening to the sheathing and the window installation flanges to the flashing.

Other openings that are often overlooked are basement windows and skylights. It was common to use metal frames with single pane glazing in basement windows. Skylights were often large “single bubble” acrylic material. Neither provides good thermal resistance. Both can be regarded as window openings. Skylights can be seen as an R-3 hole in an R-30 roof. However, the natural daylighting skylights provided can take the place of electric lighting during the day. Light tubes which direct daylight to areas like bathrooms and hallways in the core of the house can be effective. They are typically less expensive and more energy efficient than skylights, provided they are well insulated if run through an un insulated attic.

So the windows for our subject house will be wood frame with fixed and casement sash and aluminum exterior cladding. Glazing will be triple glass panel with argon gas filled airspace and low-e coating. The assembly will have a U-value of 0.24 which is approximately R-4.2. The space between rough opening and frame will be sealed with polyurethane foam and the exterior with self adhering flashing and sealant.

Doors include exterior entry doors and interior passage doors. They come in a wide range of styles and materials such as wood, wood composites, fiberglass, vinyl and metal. From a green standpoint, look for doors that are durable and made from materials that don’t have a negative effect on the human or natural environment.

For exterior doors, weather tightness, insulating value and leak free installation is important. Ornamental entry doors are usually more about looks than energy efficiency. A solid core wood door is about R-1 per inch of thickness. They have about the same insulating value as an average double glazed window, but with more potential to leak air. With a storm door, the efficiency is about R-3, which doesn’t compare to an R-24 exterior wall assembly. Insulated fiberglass or steel doors are several times more energy efficient than a solid wood door. Fiberglass is more impact resistant and conducts less heat than a metal faced door, and fiberglass can look very much like a wood door. If going with a solid wood door, look for wood that is reclaimed or sustainably harvested. Sliding glass doors are basically windows that are large enough to walk through. The same considerations for choosing and installing windows apply. Special consideration needs to be given to the sill by providing a sill pan to isolate the subfloor from water.

For interior doors, there are many styles and materials to choose from, such as solid wood to hollow core panel. Medium density fiberboard (MDF) is an alternative to solid wood. It is a solid, engineered product made of the residual fibers from the production of large wood products. It thus makes use of material that would otherwise be discarded. When considering the environment, look for wood from sustainable sources and harvesting techniques. A problem which has occurred in the harvesting of exotic hardwoods is the importing of these woods from unknown sources. Often this results in the case of clear cutting the rain forests with subsequent damage to the environment. From an indoor air quality standpoint, it is best to avoid doors that use urea formaldehyde adhesives or binders to hold the door structure together.

The exterior door for our subject house will be insulated fiberglass with a wood grain texture and a stained finish. The space between rough opening and frame will be sealed with polyurethane foam and the exterior with self adhering flashing and sealant. The door will be set on sill pan flashing. Interior doors will be MDF with a painted finish.

Siding is the front line of defense against the elements and makes an important aesthetic contribution to the architectural style of the house.

An essential element of siding is the drainage plane behind it. It is the second line of defense against the elements. It is a design feature of the exterior wall that allows any moisture that gets behind the siding to evaporate or drain down the wall and away from the building.

First among them is housewrap, such as “Tyvek” or “Typar”. It is a sheet applied over the exterior wall sheathing that sheds water while still allowing water vapor from within to escape. There are other housewrap products that have an integral drainage mat that collects moisture and drain to the bottom of the wall.

Another system is extra strong extruded polystyrene exterior wall sheathing such as “Green Guard Plygood Ultra”. These boards have an R value of 1.8, low moisture absorption and when installed as a weather resistive barrier they do not require a separate housewrap sheet.

Another method is to create what is called a rain screen. Here a waterproof membrane is applied over the sheathing. Furring strips are attached vertically over the membrane and the siding is attached to them. This creates an airspace between the membrane and the siding, ensuring that moisture will drain and the siding can dry. It also provides a break from radiant heat transfer from the sun.

Regarding siding there are several factors for evaluating whether a particular kind of siding is green. Durability is important, especially to keep prematurely failed siding out of the landfill. Another consideration is the source and manufacture of the material. Was the material produced in an environmentally friendly way?

Wood siding has a long tradition in residential construction in this country because it is so prevalent. Many like the look of wood siding but it can require considerable maintenance. Wood should be decay resistant cedar or redwood. To be certain the material was harvested in an environmentally responsible way you could obtain wood that is Forest Stewardship Council (FSC) certified.

Stucco is a cement based mixture applied in 2 or 3 coats. It is durable and does not require a great deal of maintenance. Natural building proponents like it because it is made with lime, silica sand and white cement. It is an effective fire resistant barrier. It is labor intensive to install and thus costly.

Brick is also durable and fire resistant. Basically it is baked mud and thus a natural material. From a green standpoint a downside is there is a lot of embodied energy in brick. It takes a lot of energy to fire bricks and to transport them to the building site.

Fiber cement siding is another option with green attributes. It comes in panel form as well as planks that are applied horizontally. It is more difficult to install than wood but it holds paint longer than wood, reducing the need for maintenances. It’s very durable, resists fire, rot and insects.

Vinyl siding, polyvinyl chloride (PVC), is controversial in the green world. Negative factors are its toxic manufacturing by products such as dioxin, its pervasiveness in the environment and the difficulty in recycling post consumer PVC. Many don’t like its appearance. The upside is its low cost, durability, water resistance and easy maintenance. Many conclude that the health and pollution concerns of PVC make it a poor choice.

Aluminum siding is long lasting, recyclable, moisture resistant, low maintenance and easy to install. Negatively it has high embodied energy, is easily dented and many also don’t like its appearance.

And there’s steel siding. It has the positive attributes of aluminum, is stronger and requires less energy to produce. Negatively, it is painted and coated with PVC. And to some its appearance is unattractive.

How to choose? From an environmentally sustainable standpoint, choose a long lasting material that is suitable for the local climate and doesn’t require a lot of maintenance. The raw materials should be responsibly harvested or mined. The manufacturing process should not be energy intensive or polluting. And when the material reaches the end of its life cycle it’s good if it can be reused or recycled.

For the subject house I am proposing fiber cement siding with some stucco sections.