Sustainable Window Design - Development Story

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This documents our experience in designing, building and operating the sustainable window design at the Green Garage.

Goals

    • Provide 80% of the interior lighting with natural daylight.
    • Provide adequate natural ventilation to minimize the need for mechanical ventilation whenever possible.
    • Provide a sense of security and well-being within the living building, while providing an attractive and inviting addition to the community.
    • U Factor (Thermal) < 0.30
    • Window -to-Wall Ratio (WWR) < 27%
    • Solar Heat Gain Coefficient (SHGC): E = .30; W = .30; N = .30 ; S = .55; Skylight = .55
    • Visual Light Transmittance (VLT or VT); E = .50; W = .50; N = .50; S(up) = .70; S (view)= .50; Skylight = .70


Design

  • Challenges:
    • The replacement windows in the historical facade must closely resemble the original showroom window.
    • Installing 30 windows in block openings around the building
      • Had meeting on site with Woody to discuss the options regarding area below historic windows, and areas around windows in block. Results summarized below.
    • Anchoring windows with 4" of foam insulation on outside.
    • Maintaining R values of walls at window openings.
    • Security
      • After input from the security group, the window choices are:
        • Use small windows, which are more difficult to come through.
        • use security bars
        • use security screens, (stainless steel, woven fabric).
        • use security glass, typically some type of laminated glass.


Window Design Evaluation Matrix

Through the window design process for the Green Garage, we evaluated different methods of window security, materials, window operation, and how the design might impact daylighting, energy use, and the historic appearance of the building. Our evaluation is summarized below:

(o) = neutral, (+) = positive, (-) = negative


Design Daylight Thermal Ventilation Security Historic Cost Materials Life-cycle and Maintenance
* A. Aluminum/wood
  • Casement-swing out
  • Security screen inside
o
o
o
+
o
?
o
+
* C. Aluminum/wood
  • Casement-swing out
  • Shutters inside
+
+
o
+
o
-
o
o
* F. Aluminum/wood
  • Casement-swing out
  • Security glass
o
o
o
+
o
-
o
+
* B. Aluminum/wood
  • Casement- swing in
  • Metal design security panel-outside
o
o
-
+
o
-
o
-
* D. Steel/metal old style small panes
  • Casement-swing out
o
-
o
-
+
-
o
-
* E. Aluminum/wood
  • Casement-either?
  • Sliding shutters
o
+
o
+
-
-
o
-


The results of the matrix was to pursue comparisons of options A, C and F.

Facade Design

Historic (West Elevation) One key feature is the alignment of the windows on the exterior elevations. The starting point for this is the height above the floor of the historical openings on the west (Second Avenue) wall.

New Picture.png
Brick pattern 001.JPG
  • The top of the arched window is 12'8"(+/-) above the floor. The height of the arch is 2', and the height of the short leg, or straight side of the window is 2', for a total window height of 4'. The bottom of this window determines the height of the mullion between the upper transom windows and lower casement windows on the remaining elevations.
  • Using this as a reference point, placing the new picture window and awning window below this leaves approxiamately a 16" space between the bottom of the window and the top of the limestone, which opened discussions on the best way to finish this area.
  • Options discussed:
    • Historic tile- probably dark green.
    • Raised paneling- something low maintenance.
    • Limestone
    • Brick- currently the area is filled in with a different brick than the original front.
  • At the on site meeting with Woody, he had a great idea- match the brick pattern to the pattern above the transom window area.





Remaining Elevations

Casement with Transom.png

The windows on the other elevations consist of a 2' high transom window, with a divided lite, and a 5' high casement window. The mulled connection between these two windows lines up with the arch top mull of the front of the building.

Build

Window Specs and Design

Following are original sketches from the net zero energy design meetings, where window design and placement to maximize daylighting was discussed.

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Operate