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Insulated Vinyl Siding
Foam insulated vinyl siding systems that provide thermal insulation benefits
Two new products give vinyl siding a competitive edge by increasing its energy efficiency and enhancing its impact resistance. One product is an isolative foam underlayment, custom contoured to fit snugly behind hundreds of different brands and styles of vinyl siding. The other is line of vinyl siding products fused to a foam backing material, to create an all-in-one siding and insulation system.
Progressive Foam Technologies, Inc. makes contoured foam underlayment under the brand name "Thermowall". The material is shaped to precisely fit behind nearly any manufacturer's siding profile sold in the United States. Installed over exterior walls just before placement of the siding, the underlayment provides a continuous solid backing that helps vinyl siding resist impacts that might otherwise cause cracks or dents. By adding an additional foam insulation layer, the R-values of exterior walls are increased by R-2.8 to 3.3, depending on the profile, not including the vinyl siding. The manufacturer states that the foam is made from environmentally benign expanded polystyrene (EPS), which has thermal expansion properties nearly identical to vinyl siding, and moderate vapor permeability to allow the siding to breathe.
Crane Performance Siding uses a similar concept to create lines of solid-core siding products including Craneboard and Techwall Plus. These products fuse a contoured polystyrene backing material to a vinyl exterior facing for a solid insulated wall system with an overall R-rating of 4 to 4.5, depending on the product selected. The manufacturer states that the product also helps to bridge wall irregularities, and interlocks tightly at seams to create a straight, solid finished wall appearance without the waviness sometimes associated with vinyl siding. The panel sections are up to18" high, covering nearly twice as much area as most vinyl panels, allowing installation to proceed more quickly. Application of isolative sheathing and exterior finish surfacing is accomplished in one step.
Placement Cold Air Returns
There can be no intelligent discussion about return placement without a comprehensive understanding of how both supply and return provisions affect air distribution and circulation within the conditioned space.
Nor can the conversation demonstrate intelligence regarding "cold floors" if factoring in building envelope infiltration is ignored.
A return opening may have a small sphere of influence around it. However, whatever air velocity it achieves will entrain surrounding air. The main, and very significant, difference is the rate of velocity. Returns do not have a focused air velocity, as do supplies, which emit a jet of air. The supply air jet will entrain far more air within a room, due to velocity and temperature difference. The return is drawing mixed air from a limited sphere of influence, and this air has little to no temperature difference between it and surrounding air.
The information in the Hart & Cooley document is correct. Air cannot be introduced into a room without adequate provision for an exit. It is also correct in recommending supply and return placement in accordance with the primary climatic demand; i.e. primarily a heating or cooling climate.
One other factor to consider is the physical layout of the conditioned space. High ceiling spaces will always be difficult to control, and usually require greater air exchange for an equivalent amount of floor area due to the increased volume (cubic feet) of the space. If I had my way, "green building" architecture would outlaw high ceiling interiors. We need not be confined to the old eight foot standard, but a feeling of loftiness can be had with far shorter ceiling heights than is common in our time.
Supply register placement
Windows are a source of heat gain in summer, particularly single pane windows with aluminum frames. Next hot day, with the house nice and cool, if you have single pane aluminum frame jobs in your home, stand by a window, even a shaded one. You can feel the heat on your face and skin. That's radiant heat. The hot air outdoors is heating the glass surface and the window frame...hot flows toward cold (greater heat to less heat). There will be heat transfer, and it will affect the temperature of the room where the window is.
Anyone who has ever run a heat load calculation on an average American house knows where the greatest heat gains are in summer; windows, doors, and infiltration. Ceilings adjacent to attics typically come in next, with walls close behind. In winter, heat loss is greatest via windows, infiltration/exhilaration (stack effect) and then the rest.
In my opinion, supply register placement should be a combination of the dynamics of the room, and the type of climate the house is built in. Primarily a heating climate, favor the walls/windows exposed to outdoors. Primarily a cooling climate, favor interior locations with the supply air stream aimed toward walls/windows exposed to outdoors, "washing" these surfaces with cool supply air to offset heat gain (or at least assist in getting the heat back to the a/c coil more quickly, so it can be removed again from the house). Round ceiling diffusers also work well in a cooling climate, but not as well when needed for heat in winter.
Purpose of a house is shelter
Obviously the delta between shaded 105 degree air on the outside of a single pane of glass and 75 degree indoor air isn't as great as mid to late afternoon sunlight beating on this same piece of glass with the same air temperature outdoors. Allowing direct sunlight to enter a house during hot weather is just asking for trouble, even with better windows. I suppose my point is that if more thought from an architectural standpoint was given toward shading windows and doors, the structure itself can help reduce heat gain to the interior. I find it patently ridiculous, from an architectural standpoint, that so much of our housing stock is architecturally poor for the climate in which it resides. On one side you have architects and builders stuck in the "form follows function" school, and on the other "function follows form". The minority appears to be "form and function as one".
The primary purpose of a house is shelter. In our time the word shelter carries far more weight than a log cabin of years ago. Back then it was to get protection from the cold and keep from being eaten by large animals or bitten to death by bugs. Now, those elements remain, but added to that are security, summer comfort, indoor air quality, and respite from a hectic world. Many modern houses can achieve these things, but they do so with high energy consumption, which works against a sense of shelter due to high operating costs.
So, we're stuck with a large housing stock, architecturally wrong for most climates, requiring remedies to keep from driving the occupants to the poorhouse. What to do? Insulate, better windows and doors, reduce infiltration, more exterior shading when possible, higher efficiency HVAC equipment that is properly installed and balanced. Do we do all those things every time an existing house is eating the owner's wallet alive? Not always. It's either thrown more equipment at the structure, or makes the structure an airtight coffin that is unhealthy to live in. A balance is in order.
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