DPO Construction LC

Structural Insulated Panels SIPs (Video)

Below is a video from the Alliant Energy PowerHouse series about Structural Insulated Panels (SIPs).

Sprayed Polyurethane Foam Insulation Installation and Benefits (Video)

Below is a video from the Alliant Energy PowerHouse series about the cost saving benefits sprayed polyurethane foam insulation.

Working with SIPs (Photos)

In these photos, we see examples of working with SIPs.

Perspectives on Energy Efficient Construction

by Don Otto, DPO Construction LC
www.dpoconstruction.com

“All this high-efficiency stuff must be expensive and I probably can’t afford it.” This viewpiont is a misconception some clients have when I encourage them to consider a high performance approach to building a new home. Actually, by making some intelligent choices, the home doesn’t have to cost a bit more. Consider as well that there are multiple bonuses that come along with the low utility bills: durable, low maintenance construction, great indoor air quality with draft-free fresh air, quiet rooms with lots of natural light. All come together in the same package. Here are some of those intelligent choices.

• Start with design. Build only the rooms you use. Create private alcoves within public spaces. The more useful the design, the more enjoyable it is to live in. The smaller the house, the less it costs to build and operate.
• Keep the building dry. Moisture rots wood and promotes mold, which could cause health problems.
• Make use of frost-protected shallow foundations. Insulating the footing reduces excavation and foundation costs and keeps floors warmer.
• Start with an energy recovery ventilation system and build a tight envelope around it. Reducing air leaks eliminates drafts and seals out noise. Proper ventilation is specified by the American Lung Association for their Health House ®. A tight envelope with proper ventilation does more than anything else to reduce utility bills and make a comfortable home. Besides, the savings in utility bills more than offsets the increased monthly mortgage costs of the equipment.
• Use good windows and doors. Cheap windows are not only drafty, heat radiates right out through the glass. Be sure your windows have low-e coatings that reflect radiant heat back inside the house. The coatings keep the window warmer at night and reduce daytime glare and fabric damage from ultra violet.
• Take advantage of the sun and the site. What can feel better than a warm, sunny window in the winter?
• Size the mechanical equipment properly. Oversized equipment costs more and operates less efficiently because it starts and stops more frequently.

A Wood Foundation… How Long Can it Last?

by Don Otto, DPO Construction LC
www.dpoconstruction.com

A wood foundation in Iowa? You have to be kidding. Won’t it leak? Won’t it rot? Can it be strong enough? Is it safe? Does it have any advantages?

Wood seems like an unlikely material to build a foundation with until you look at all the things a foundation needs to do and address each one. Let’s go through them.

Manage Water (Won’t it leak?)
Even poured concrete foundations leak if you don’t manage water. Water coming up from below needs to drain into a sump pit and be pumped away before it reaches footing height. Water from above is managed by proper grading away from the house. Gutters can catch water from the roof, or you can lay plastic sheeting covered with river rock on the sloped ground under the eaves, or both.

Water along the side walls isn’t as much of a problem since gravity is pulling it straight down, not pushing it sideways. Nevertheless, walls are covered with a continuous later of plastic sheeting over a drainage plane of asphalt-saturated felt.

Wood foundations are set on a bed of washed rock under the footings and floor. The rock serves as a continuous layer to drain water away and keep the floor and foundation dry. If you also have a wood floor, spraying urethane foam insulation directly on the rock, between the joists, seals the entire floor from soil gasses, keeps the floor warm and locks the whole floor in place.

Finally, wood foundation walls are backfilled half way up with washed rock. Any water that makes it through the top is allowed to drain right down to below the footing. If you imagine it in cross section, the whole foundation and floor are enclosed in a basket of washed rock.

Come to think of it, that’s the way all foundations should be built.

Free from decay (Won’t it rot?)
The wood used for foundations is treated with salts that make it unusable as a food for termites, bacteria and fungi. The salts bind to the cellulose and there is a standard concentration of those salts (0.6 lbs. of salts per cu. ft. of wood) that is used for foundation grade treated lumber.

Structurally strong (How do you make it strong enough?)
We all know wood walls can hold up several stories of height, but over time, soil acts like a thick liquid, and can exert lateral loads (sideways pressure) on the walls. If foundation walls sit 4 ft or less in the ground, structural designs can be determined from code-approved tables. But foundations deeper than 4 ft in the ground need to be engineered to withstand the lateral loads.

You might think that specifying the size and spacing of the studs to keep them from buckling is all there is, but keeping the walls in place, at the top and the bottom, especially during backfill, is more important. How the walls are fastened to the basement and main floors determine how long the system will last. Lateral loads need to be calculated, the size, type and spacing of fasteners need to be specified and conscientiously installed.

I’ve seen several wood foundation failures, and every single one happened not because of wood rot, but because the builder thought the specs were excessive, and must have said “I don’t need to do that!”

Healthy (Is it safe?)
You wouldn’t want to drink the salts used to preserve wood; they’re poisons. Even the new formulas without arsenic can be toxic. During the treatment process some excess salts remain soluble and don’t combine with wood, and could potentially leach out of the wood if it gets soaked. But remember, wood foundations are designed to be kept dry, so there should be minimal risk of exposure to the salts.

Durable (How long can a wood foundation last?)
Centuries. Easily.

Are there any advantages?
Wood basements can feel warmer. Concrete absorbs a lot of radiant heat from your skin, and can make a basement feel cold, even if the air temperature is warm. Wood absorbs much less radiant energy. While there’s no denying a concrete basement floor with in-floor radiant heat feels great, you often don’t need the extra heat in a wood floor to feel comfortable.

Wood foundation materials take less energy to make. The heat needed to make anhydrous Portland cement takes a large amount of energy, and wood is a renewable resource.

Wood basements can be easily insulated and finished with no additional structures. Wiring can be run through the studs, and drywall can be fastened with no additional stud walls.

Wood foundations can cost less. The savings increase the farther out of the ground the foundation sits. Even a foundation 7 ft in the ground can be significantly less; saving funds which can be applied to a geothermal system, for example.

How Does a Geothermal Heat Pump Work?

by Don Otto, DPO Construction LC
www.dpoconstruction.com

In short, just like your air conditioner, except that the heat exchanging tubes are in the ground, instead of in the air. In a geothermal system, water-filled tubes buried in the ground pick up the ground’s heat—about 50° to 55° year round—and circulate that water to the heat pump. But how do you warm your house with 50° water?

You have to use an intermediate device that can concentrate the heat—a compressible gas. When you compress the gas from a large volume to a small volume, you also compress the larger volume’s heat, so by definition, there’s a lot more heat per unit in the smaller volume. In simpler terms, it’s hotter. Not surprisingly, the surface of what’s holding the compressed gas gets hot, too. Now, if you blow air across that hot surface, you can heat your house. (If you’ve ever pumped up a car tire with a bicycle pump, and felt the metal connector between the hose and the barrel, you know it can get hot!)

But how does the heat from the water get transferred?
When you blow air across the hot surface, you take the heat out of the compressed gas (cooling it), and the gas turns into a liquid. In order to turn it back into a gas, you have to warm it up and take the pressure off (give it a place to expand into). At this point in the cycle the fluid is now just about freezing temperature (32°), so the 50° water from the ground has plenty of heat to warm it up.

When you want to cool your house, the system runs in reverse: heat from the house expands the liquid into a gas and the warmed water in the ground loops stores its heat in the earth.

Ground source (geothermal) heat pumps have several advantages over fuel-burning furnaces. They’re environmentally friendly and efficient. Since the energy to heat your house comes from the sun and the earth’s core, all you pay for is the electricity to run the compressor, the blower and the water pump. It’s common to get 3 to 5 times the energy out of a heat pump than what you put into it.

Geothermal systems help heat your hot water. Compressors are not 100% efficient and produce a little “waste” heat (called “superheat”, since the compressor’s job in the heat pump is to make gas hot). Today’s geothermal systems have a water-filled jacket, called a “desuperheater” which takes that extra heat and pumps it into your water heater. Every time the compressor runs to either heat or cool your house you’re getting “free” hot water.

Geothermal systems are versatile and quiet. It’s really easy to have forced-air heating and cooling, or radiant in-floor heat, say, in your basement or garage.

Geothermal systems are affordable. While they’re more expensive up front—roughly twice what a natural gas system costs, the lower monthly utility bills offset the increased mortgage payments. A 3,000 conditioned-sq. ft. home in Solon I built in 2004 is heating for $0.86 a day, even including the sub-zero January weather!

How I Build Green Homes

by Don Otto, DPO Construction LC
www.dpoconstruction.com

Living in harmony with our environment means we should be more than just wise consumers of our natural resources, we should be their stewards. If we are to keep planting our home’s foundations in the ground, it’s only responsible that those homes make a small environmental footprint. We make a difference in the rate we use materials, and in the energy we consume to keep us comfortable.

DESIGN
Green building starts with good design— not just curb appeal, but homes that meet our functional and emotional needs. Settling for less is poor value, and building spaces that are seldom used is a waste of resources; yours as well as nature’s.

In designing a home, I like to form a design team, composed of the owners, a designer and myself. Owners define the goals and the budget; the designer provides the experience and creativity to make all the pieces fit. I provide the details that ensure energy efficiency, air quality and durability, keep a pulse on the costs, and during construction, manage the project until you move in.

I encourage clients to make all the spaces count, and build only the floor space they need. (If you’re not going to use a formal dining room, for example, don’t spend the money to build it. Use the savings instead to reduce the cost, or to better afford nicer things, like custom cabinetry, efficient appliances, or a geothermal system.)

The savings can be eye-opening. Here’s a real-life example: The original size of a home plan in Solon started out at 2,500 sq. ft. Using Sarah Susanka’s “Not-So-Big” techniques— providing abundant light, long sight lines, and creating private spaces within larger rooms, for example— we whittled off 500 sq. ft., creating a home with spaces that are well used and a have comfortable human scale. Giving those 500 sq. ft. a conservative value of $100/sq.ft, we saved the owner $50,000! The savings allowed him to afford many luxury upgrades that only a larger budget would have permitted. I don’t know of anything else in home building that has such a significant effect on both up-front, and lifetime-operating costs.

VENTILATION
We spend well over 90% of our time within enclosed spaces. With respiratory diseases like asthma ever increasing, maybe we should pay attention to where we do most of our breathing. In contrast, have you ever opened a bedroom window in winter and noticed, after only a short time, how much fresher the room feels? Imagine having your whole house feel that fresh year round, but without cold drafts or high utility bills. Because I believe a healthy indoor environment is most important, I start the energy design with an ERV, an energy recovery ventilation system.

The ERV brings in all the fresh air you need, recovers the heat from the exhaust air, and works to keep the indoor humidity at conditioned levels. Simple controls allow you to tailor operating the system to your own comfort level. As a bonus, locating the system’s exhaust ports in bathrooms eliminates the need for bathroom fans, and it’s almost silent when it’s on

THE BUILDING ENVELOPE
Since all the fresh air comes in with the ERV, it only makes sense to make the building envelope as airtight as possible. I’ve found that Structural Insulated Panels, (SIPs) provide that tight envelope, along with being stronger, they are faster to build with, better insulating, use less wood and cost about the same as stick built. SIPs are built from slabs of foam insulation with oriented strand board (OSB) panels adhered to the faces. There are no studs. The only lumber used is in the top and bottom plates, corner reinforcing and the around doors and windows. Other systems, such as insulated concrete forms (ICFs) also work well.

INSULATION
Sprayed polyurethane foam insulation helps to complete the tight envelope. It’s sprayed continuously from the top plate, up the under side of the roof deck, and down to the opposite wall, creating an airtight cap. This also allows design freedom to have vaulted ceilings and recessed lights without any additional air sealing or loss of energy. It also allows heat ducts or plumbing to be installed above the ceiling without extra insulation. The same kind of insulation is sprayed on the basement’s rim boards, walls and under the basement floor, creating an airtight building “cocoon”.

WATER MANAGEMENT AND DURABILITY
When it rains, materials get wet. If organic materials stay wet, they promote mold growth and they rot. Water is necessary for all organisms, like molds, to grow. The key to making materials durable is to keep them dry, let them dry, or use materials that don’t rot. Luckily, making things last is something we can control with good water management practices, like proper flashing and drainage planes. Consider this: doubling the durability of a material decreases its environmental impact by half.

HEATING AND COOLING
Geothermal systems use a renewable resource—the heat from the sun and the core of the earth—to heat and cool your home. While the up front costs are roughly twice that of a natural gas system, they are extremely efficient and cost much less to operate. Since the cost of heating equipment is included in a mortgage, the lower utility costs can more than offset the increased mortgage payments. For the seven months between October 2005 and April 2006, which included two sub-zero spells in December and January, the heating bills for a home I built in Solon totaled $181.00, or about 86 cents a day!

PUTTING IT ALL TOGETHER
We want our homes to be comfortable, keep us safe and healthy, and be durable and efficient. The weather imposes conditions that all homes have to live with, and following good building science principles provides the best methods to handle them. Good design provides that emotional connection that makes our homes truly enjoyable places to live. Paying respect to both is the best way I know to build a home.

Why Building Green is Important

Building green helps us preserve the earth we enjoy and rely on…