On this page you will scroll down to see discussions of many of the various applications we chose to use in our current focus new construction project at 5803 North 16th Street in Arlington.
The home is designed with four full bedrooms, a loft and 4.5 baths and is meant to serve the modern family. As an infill project, it is situated in a close in Arlington neighborhood, one block from: Westover shops, Westover Library, Swanson Middle School, and the Westover school park and ballfields. It is less than a mile to the Metro and a block from a main bus line.
The home is in the US Green Building Council's LEED for Homes Program and is in line to be one of the first new residences in the Washington Metropolitan area with a LEED Gold and possibly even Platinum rating.
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Frame and Structure:
There are many problems with today's standard stick built construction. To name just a few: 1) When materials are cut on site, a large amount of material is wasted - wood is recyclable commodity and we should maximize that wherever possible; 2) Efficiency- homes - stick built on site - are often leakier than a salad strainer. Joints aren't tight and the insulation that follows behind is never quite as good as it needs to be. We went with SIPs and if you go to our project photos section you can see them in action. We used an experienced installer - Intellistructures - and they were great to work with. See a discussion below of various alternatives.
Some Alternatives:
ICFs - Insulated Concreted Forms are like styrofoam legos. With Polystyrene on two sides held together by plastic connectors, ICFs are stacked in the form of you outside wall and then reinforced concrete is poured in between. ICFs are now regularly used for basement walls and they provide excellent insulation for that and for the entire strucutre. There are very few leaks in an ICF building as long as you seal your window casements. Construction is easy. One floor goes up at a time, with time in between each for the concrete to cure.
Prefab - There are different levels of prefab construction from the most basic SIP to complete homes delivered on site. This is not your 1980s doublewide rolling down the road. Rather, prefab today can be as customized and beautiful as the most beautifully hand crafted home.
SIPs - Structural Insulated Panels, are the simplest form of prefab, and it is probably going a bit far to say "Prefab". SIPs are simply a sandwich of structural strength sheathing (OSB) on the outside and poystyren foam on the inside. SIPs eliminate the need, in general, for studs and insulation, since both are contained in each SIP. SIPs are growing in populatiry each year. Using your home design, the SIPs can be precut to your home design, or standard panels can be used with stick built features where customization is needed.
Panelized construction - Panelized construction is relaly SIPs Plus. Your house's shell is built in a factory, with windows inserted, etc. Then the structure is assembled on site. With Panelized construction, you have even greater constrol over waste and energy efficiency, ensuring that windows are sealed in place. On site construction time is reduced - A whole 4000 sq foot home can be dried in within 4 weeks.
Extensive Panelized construction and Modular - In this scenario, SIPS Plus Plus, the whole house, including plumbing chases and electrical is built into the wall panels in the factory and simply assembled on site and then fixtures are dropped in. If you saw this on the road it might look like your 70s style double wide, but don't mistake it. This is top shelf stuff. Beware of extraordinarily long design times. If your home is custom, they will take a long time designing the mecahnical systems so that they can be constructed in the factory. This works for some applications, and not for some.
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INSULATION: See this Chart that I took from from The Encyclopedia of Sustainable Living website. It identifies all the different types. We are goin with SIPs as discussed before so they are preinsulated with EPS. We are blowing Icynene into all the rest of the cavities.
Wherever you see fiberglass, there is a natural alternative. We prefer rigif foam or blown in foam wherever possible for the tightest seal. This is the most expensive, but it will recover its cost pretty quickly through energy savings.
Form
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Insulation materials
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Where applicable
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Installation method(s)
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Advantages
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Blanket: batts and rolls
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Fiberglass
Mineral (rock or slag) wool
Plastic fibers
Natural fibers
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Unfinished walls, including foundation walls, and floors and ceilings.
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Fitted between studs, joists, and beams.
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Do-it-yourself.
Suited for standard stud and joist spacing, which is relatively free from obstructions.
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Concrete block insulation
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Foam beads or liquid foam:
Vermiculite or perlite pellets
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Unfinished walls, including foundation walls, for new construction or major renovations.
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Involves masonry skills.
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Autoclaved aerated concrete and autoclaved cellular concrete masonry units have 10 times the insulating value of conventional concrete.
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Foam board or rigid foam
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Polystyrene
Polyisocyanurate or polyiso
Polyurethane
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Unfinished walls, including foundation walls;
floors and ceilings;
unvented low-slope roofs.
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Interior applications: must be covered with 1/2-inch gypsum board or other building-code approved material for fire safety.
Exterior applications: must be covered with weatherproof facing.
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High insulating value for relatively little thickness.
Can block thermal short circuits when installed continuously over frames or joists.
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Insulating concrete forms (ICFs)
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Foam boards or foam blocks
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Unfinished walls, including foundation walls, for new construction.
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Installed as part of the building structure.
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Insulation is literally built into the home's walls, creating high thermal resistance.
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Loose-fill
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Cellulose
Fiberglass
Mineral (rock or slag) wool
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Enclosed existing wall or open new wall cavities;
unfinished attic floors;
hard-to-reach places.
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Blown into place using special equipment; sometimes poured in.
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Good for adding insulation to existing finished areas, irregularly shaped areas, and around obstructions.
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Reflective system
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Foil-faced kraft paper, plastic film, polyethylene bubbles, or cardboard
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Unfinished walls, ceilings, and floors.
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Foils, films, or papers: fitted between wood-frame studs, joists, and beams
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Do-it-yourself.
All suitable for framing at standard spacing. Bubble-form suitable if framing is irregular or if obstructions are present.
Most effective at preventing downward heat flow; however, effectiveness depends on spacing.
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Rigid fibrous or fiber insulation
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Fiberglass
Mineral (rock or slag) wool
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Ducts in unconditioned spaces and other places requiring insulation that can withstand high temperatures.
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HVAC contractors fabricate the insulation into ducts either at their shops or at the job sites.
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Can withstand high temperatures.
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Sprayed foam and foamed-in-place
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Cementitious
Phenolic
Polyisocyanurate
Polyurethane
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Enclosed existing wall or open new wall cavities;
unfinished attic floors.
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Applied using small spray containers or in larger quantities as a pressure sprayed (foamed-in-place) product.
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Good for adding insulation to existing finished areas, irregularly shaped areas, and around obstructions.
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Structural insulated panels (SIPs)
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Foam board or liquid foam insulation core
Straw core insulation
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Unfinished walls, ceilings, floors, and roofs for new construction.
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Builders connect them together to construct a house.
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SIP-built houses provide superior and uniform insulation compared to more traditional construction methods; they also take less time to build.
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HVAC Systems: Natural gas, heat pump, radiant, geothermal
We have decided to go with a Geothermal HVAC system. It saves almost 50% on your energy costs and is just about the coolest no brainer technology out there.
Here is some info on geothermal I grafted from an energy website
What is a geothermal heat pump?
A geothermal system, also called a ground-source heat pump, works on a simple premise: the earth below a certain depth (the frost line, usually about four feet deep), is a constant temperature of about 50 degrees throughout the year.
Heat is taken from the ground and transferred to the air in your facility during the winter; the process is reversed during the summer.
The loops of piping are buried in the ground on your property, either vertically or horizontally. The ground loop is connected to a pumping module inside your building, where a mixture of water and liquid antifreeze is circulated through the system.
As the liquid moves through the underground pipes during winter months, it absorbs heat from the earth. When the heated liquid reaches the heat exchanger, it is converted through the refrigerant process to warm air and circulated through the building.
To cool your facility in summer months, the system simply works in reverse with the flip of a switch.
Significant energy savings
A geothermal system can lower your heating bills up to 50 percent and lower your cooling bills up to 30 percent, when compared to a conventional system. Heat from the ground is free, and the only electricity needed is for circulation.
This could mean a payback in as little as two to seven years! And don't forget: ground-source heat is naturally renewable and non-polluting. No precious natural resources are wasted.
And for extra energy savings, you can add an attachment called a "desuperheater" that connects your heat pump to your water heater. When the energy from the heat pump isn't needed, it's diverted to your water heater so you'll be getting virtually free hot water.
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Energy: Passive - Geothermal, Passive Solar, Solar hot water --- Active - Wind, Solar PV
I am sure that some will criticize how I have categorized these or that I haven't included some other form of energy generation, but I have tried to set it out in a way that makes sense to me. Passive is taking advantage of something that is already there and not converting it into electricity. Active is when you convert it.
We will be using a combination of Solar PV and Geothermal. You have seen the discussion of geothermal above as for solar, it seems like pv will work great for us, but the installation costs can take your breath away.
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WATER: conservation and runoff prevention.
In our region of the country, runoff prevention is a huge issue. The Chesapeake Bay is one of the most sensitive ecosystems in the country and every time it rains hard (which it does often), pllutants goe streaming off of houses, driveways and playgrounds - into our storm sewers with a next stop - The Chesapeake Bay. This is a killer for us and if we don't change our habits, we are doomed to kill off one of our most precious regional resources for food, recreational use and biodiversity. Conservation is also important and plays into runoff prevention.
We are going with a combination system - greenroof and cistern. With a combination of cisterns, rainbarrels, and greenroof, we will be able to filter and slow down 100% of the runoff from the roof.
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