The Town of Hudson, MA
78 Main Street, Hudson, MA 01749
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Library Window Project

The Library Window Project is finally complete!  The first windows were installed in late February & with exceptions due to rain delays, installation moved along steadily ever since.  Installation of the windows located in the historical section of the building were completed in March.  Installation of the large curtain-wall windows in the rear section of the building were completed by the end of June.

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What was done exactly?

  • Each window was replaced with double or triple glazed energy efficient windows, depending upon the section of the building.
  • Windows are aluminum clad on the exterior, but wooden on the interior, to match existing historical architectural elements.
  • Interior shades were replaced with energy efficient solar shades.  Shades now have a low solar transmittance (10%) and 48% greater reflectance than the original shades.
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Before & After

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Before - Rusted and failing aluminum panels allowed water to
permeate the building envelope.

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After - New panels with flashing direct water away from the building.
Areas behind the panels were damp proofed to further seal the building envelope.

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                                                Public information poster on display in Library

In February 2010, the Department of Community Development won an Energy Efficiency and Conservation Block Grant (EECBG) in the amount of $150,000 to replace exterior windows in the Hudson Public Library.  The grant was provided through special round of federal stimulus funding through the Department of Energy Resources.  

The Library Window Project will increase thermal efficiency at the Hudson Public Library, an historic building built in 1905. While a later addition in 1967 doubled the size of the library, its oversized metal windows are single pane glass units which are known for being the least energy efficient.  The older section of the building still had wood-framed windows original to the 1905 building.  The project replaced 55 window openings, each comprised of 117 individual window units.  It is estimated that the degraded windows made up approximately 30% of the building’s total exterior!  The Department of Community Development and Glenn Davis of Davis Architects worked with the Hudson Historic District Commission to ensure that the new windows reflected the historic character of the building.

The EECBG grant funded the replacement of the large curtain panel windows in the rear section of the building.  The replacement of the windows in the historic section of the building were replaced with funding through the Community Preservation Act, approved by Town Meeting vote November 15, 2010.  

The Library Window Project was completed in two phases.  Phase 1: the original historic section began installation in February 2011.  Three to five windows were installed per day in this section.  Phase 2: the 1960's rear addition began installation in March 2011.  These windows were more complex to install and were installed at the rate of one per day.  Special care was taken to section off each window opening during installation to protect books & other Library amenities from dust & debris.

Calculations & Energy Reductions

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  • What is Low E glass?
The Library Window Project was centered around the installation of the most energy efficient windows available that fit our historic criteria and budget.  All windows in the Library are Low-Emissivity (Low-E) glass.  Emissivity refers to the ability of a surface to absorb or reflect heat.  An energy efficient glazing technology, Low-E glass coatings work by reflecting or absorbing light (heat energy).  The thickness of the Low-E coating (double or triple glazed) dictates how well the window will reflect heat.  The windows in the historic section of the building are double glazed.  The large curtain-wall windows in the 1960's addition in the rear of the building are triple glazed.

  • What is a U-factor?
The energy efficiency of a window is measured in terms of thermal transmission, or U-factor.  U-factor measures the rate of heat transfer through a product, more simply, how well a product prevents heat from escaping. Therefore, the lower the U-factor, the lower the amount of heat loss, and the better a product is at insulating a building.  On a ratings scale typically falling between .20 to 1.2, the new windows in the historic section of the building have a U-Factor of .30.  The new triple glazed windows in the 1960’s addition have a U-Factor of .24, the lowest heat transfer rating available in a triple glazed unit.  

  • What does SHGC mean?
In addition to the U-Factor, windows are also measured by its Solar Heat Gain Coefficient (SHGC).  SHGC measures how well a product blocks heat from the sun.  Low-E glass has a low SHGC.  The lower the SHGC, the better a product is at blocking unwanted heat gain.  An SHGC value of 0 indicates that the window functions like a wall, essentially preventing any solar energy from entering the building.  A high SHGC value of 1 indicates that the window functions like an opening, allowing all solar energy in.  

Considering that windows need some sort of visible light transmittance, the SHGC ratings scale usually falls between .15 and 1.  The new windows in the historic section of the building have a SHGC of .28, meaning only 28% of solar heat is transmitted.  The new triple glazed windows in the 1960’s addition have a SHGC of .24, with only 24% of the solar heat transmitted.  

Estimated Reductions & Savings… PER YEAR:

  • 1,500 - number of gallons of heating oil conserved
  • 5,800 - amount of kilowatt hours of energy conserved
  • 40,000 – pounds (or 20 tons!) of carbon dioxide (CO2) greenhouse gas emissions reduced
  • 40% - reduction in heating fuel costs
  • $6,000 - savings in heating fuel costs
  • $1,000 - savings in electricity
This amounts to a savings of $88,000
over the next 10 years while reducing
200 TONS of carbon doxide (CO2) emissions!

In the News! ~ Click here for articles, blogs and press releases.

Typical Problems

These are some examples of typical problems we were facing:

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                Exterior Rot                                    Rotted Sills                             Windows Won't Close

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            Water Damage                                Rusted Doors                              Cracked Panes

Click here for more photos.

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Rusted panels in the large curtainwall windows were replaced with prefinished raised panels.

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          Existing curatinwall window with                              Architectural detail of new curtainwall
                     rusted panels.                                                            windows with raised panels.

Click here for architectural plans by Davis Architects.

Project sponsored and substantially funded by:

The US Department of Energy’s (DOE) Energy Efficiency and Conservation Block Grant (EECBG) program, with funds appropriated by the American Recovery and Reinvestment Act of 2009 (ARRA), Public Law 111-5.