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Movable Insulation
by William K Langdon
ISBN:402 pages   5.5x8.5 inches [size]

With easy construction plans for easy insulated curtains, a huge variety of panels that you can put inside your windows, outside, and fold up/down and much more. From an extraordinarily talented author, this 379 page book is an absolute must have for any homeowner that wants to stop heat loss now!


Movable Insulation


Windows, Glass Doors, Skylights, Greenhouses and Solar Hot Water Heaters

If your home is a typical one, it loses 25 to 30% of its heat through its windows. If you have particularly large window areas, this heat loss may be 50% or more, even if they are made of insulating glass and face south! In this book you will find numerous movable insulation systems that will cut the heat loss through these windows in half!

Insulation has traditionally been a fixed item placed permanently inside walls, ceil­ings, and floors of a building to trap heat and create an effective thermal envelope. Insulation is most effective when this envelope is continuous and complete, with no gaps or weak spots. Windows penetrate this envelope and allow heat to escape. Movable insulation covers these gaps in the building's thermal envelope at night. Because this insulation is movable and not stationary, it can be removed during the daytime to allow light and solar heat to enter.

Many of the movable insulation systems in this book are first-generation items, cre­ated by people who are building and living in energy-responsive environments. Many can be home-fabricated and are fully diagrammed and described in Parts II through VI. Systems which are ready-made and available as off-the-shelf products are also included in each chapter. As you read this book, you will learn how much you can save by adding thermal protection to your windows.

The information here can also be useful in commercial and institutional buildings where abundant use of single glazing is caus­ing a colossal loss of heat. This book could also aid those architects and engineers who are designing buildings which will respond to natural energy cycles. Window insulation speaks a new design language that is still foreign to many architects, and this guide helps to reveal some of the essential design details and criteria needed to apply such insulation. A method of assessing the economic return from a window insulation system in Appendix II and the listings of products, hardware, and compo­nents in Appendix III may be of particular interest to design professionals.

All practical solar designs begin with an energy-efficient design. Movable insulation reduces heating loads, thereby reducing the collector area required. In passive solar heating systems, movable insulation is often an integral component, helping heat-storage walls to retain their heat for longer periods of time. In cold climates, movable insulation enables the solar greenhouse to maintain growing temperatures without a supplemental source of heat. By employing movable insulation to enhance solar water heating systems, pumps, collector panels, and heat exchangers can some­times be eliminated altogether!

Beyond the heat you save from these sys­tems, there are additional benefits. Solar heat gain can be enhanced and controlled, privacy can be insured, and the spaces where these systems are employed take on new depths of relevance to their surrounding environs. The nuts and bolts of these systems, the dollars you can save, and their means of construction and operation are all fully examined in this fantastic book!


Window Air Infiltration Losses

Infiltration losses are difficult to measure precisely, yet they can be very significant. A single-glazed window that is loose and poorly fitted can lose twice as much heat through the air cracks (or through infiltration) than through the glass area itself (or through conduction) (see Figures 2-1 a and 2-1b). The amount of heat lost by air leakage depends not only on the size of the cracks around the sash and frame, but also on the outside wind speed and direction. Table AIV-1 in Appendix IV shows the number of cubic feet of air flow per linear foot of crack for several different types of sash treatments and wind speeds.


Figure 2-15 shows the net heat transfer through several types of windows facing south, east, west, and north throughout the heating season in Madison, Wisconsin. The line in the center is the break-even line. Points below this line indicate that the glass is losing more heat than it is gaining in a given month. Those portions of the curves above the line indicate net gains of energy.

South-facing windows are the most beneficial. A window assembly facing south is a net provider of heat, except for single glazing which is a net loser of heat, November through February.

East-facing or west-facing windows all lose heat in Madison during December and January, although with double glazing and R-5 night insulation, these losses are small. East and west windows are most beneficial during the springtime when the days are longer and much more sun can shine on them during early morning and late afternoon.

North-facing windows are invariably heat losers with single-glazed units dipping way below the others, as one would predict. However, before you entirely write off north-facing windows, note that this graph shows only heat transactions and does not include the energy benefits from natural lighting nor any aesthetic considerations.

The heat lost and gained through windows varies not only according to the window orientation and season, but is also determined to a great extent by the climate or location of the building. Madison, Wisconsin, was chosen here because it has very cold and sunny winters. Graphs for several other cities are shown in Figure 3-1.


Many older homes have windows with numerous small panes of glass, usually in the upper sashes (see Figure 5-6). This multipaned design makes it difficult to place a panel close to the glass. A simple solution, however, is to cut a 3/4-inch beadboard section—thicker if necessary      to fit into each section of glass. Fasten these pieces to the glass with adhesive magnetic clips and then take another sheet of beadboard cut to the size of the entire window sash and glue it to these panels. When the glue dries, remove the panel and you will have a single pop-in shutter with pieces that fit into each section of glass.


Bottom Seals - Because air, cooled by a window, tends to fall to the floor, the bottom seal on a curtain is the most important one. A versatile bottom seal for draperies is very difficult to design. No single method suits all window situations. A variety of bottom seal options are described below:

       Permanent magnetic strip—This system provides an excellent seal that is easy to operate in most cases. A magnetic strip adheres to the window side of the liner hem and mates with a magnetic strip on the wall or on trim below the window. Care in installation is required so that the magnetic strips mate properly (see Figure 6-3a).

     Elastic cords or metal spring rod (suggested by Clare Moorhead of Con­servation Concepts, Ltd.)—Dress elastic or elastic cord can be used to make a bottom seal for narrow windows if the windowsill projects at least 1 inch from the wall. The elastic cord attaches to a cup hook (a 1-inch screw or nail can also be used), which is mounted just below the windowsill on each side of the window. The curtain is firmly sealed by pulling this cord out, tucking the bottom of the curtain under it, and letting it snap back in place (see Figure 6-3b). "Sash rods," which are long metal springs, can be used in the same manner as the elastic, although adjustments are some­times required. They can be obtained in drapery hardware departments.

      Bar with brackets (suggested by Bill Shurcliff)---Brackets can be installed on each side of the windowsill to receive a bar or rod. The brackets should be carefully located so that the bar presses the curtain snugly against the windowsill when it is lifted into these brackets. This bar can be a decorative curtain rod to match the curtain rods above. When the curtain is open this rod can hang from the brackets by a chain or rope (see Figure 6-3c).

    Spring clamp strip—A 1-by-4 wooden strip can be mounted horizontally on the wall below the sill with spring-loaded (self-closing) hinges. The hinges for this wooden clamp strip should attach to the wall just below the bottom hem of the curtain. When the curtain is drawn, the wooden strip is opened to catch the curtain hem and then closed to clamp the curtain tightly to the wall with the spring action of the hinges (see Figure 6-3d).


Before applying any type of outside shading, an examination of the hourly location of the sun during each season is necessary. Figure 11-1 shows the sun path for a middle (40-degree) latitude location (Philadelphia, Pennsylvania; Columbus, Ohio; Denver, Colorado) on December 21, March 21, September 21, and June 21. The sun rises at 7:30 A.M. on December 21, reaches an altitude of 21 degrees at 10:00 A.M., 26.5 degrees at noon, back to 21 degrees at 2:00 P.M., and sets at 5:30 P.M. On March 21 and also September 21 the sun rises at 6:00 A.M., reaches an altitude of 50 degrees at noon, and sets at 6:00 P.M. On June 21, the sun rises at 4:30 A.M., reaches an altitude of 37.5 degrees by 8:00 A.m., 59 degrees by 10:00 A.M., 73.5 degrees at noon, 59 degrees at 2:00 P.M., 37.5 degrees at 4:00 P.M., and sets at 7:30 P.M.


The fiberglass blanket in this design is attached to a curved sheet of galvanized steel that reflects sunlight onto the tank (see Figure 18-4). Aluminized Mylar is glued to this galvanized sheet to increase its reflective properties. Hinged 2-by-4s at each end of the tank hold the reflector in position and guide it as it closes. These arms are shifted seasonally to adjust the tilt of the reflector to winter and summer sun angles. A waterproof vinyl fabric covers the insulation on the outside. Carpet scraps are glued along each end and the bottom of the tank to make a tight seal when the cover is closed.


Movable Insulation
by William K Langdon
ISBN:402 pages   5.5x8.5 inches [size]