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Example of "Tilt and Turn" operable windows - from Storm Seal UK LTD


Definition


In the context of resilient building, "operable windows" refers to fenestration that are designed to provide ventilation, especially in the case of power outages caused by extreme heat event. They may also serve as a means of egress in emergency situations. Ventilation provided by operable windows provide cooling without the use of electrical power. This provides an opportunity for energy savings during temperate seasons and may prevent heat-related illness or even death, in the case of extreme heat events.[1]



Issues Addressed


The spike in energy use experienced during major New York City heat waves has been enough to cause major power failures throughout the city in recent history. In these situations, building occupants are forced to seek shelter from the extreme heat or to shelter in place. For some, health or mobility challenges may result in their choice to stay in their apartments. New York City Department of Health and Mental Hygiene statistics have confirmed over 100 deaths within the last decade associated with heat strokes occurring during power failure.[2]
Often, the threat of heat deaths impacts those most vulnerable, including the elderly, people with disabilities, or with health stressers, such as cardiovascular disease. [3]

Recent analysis produced in joint research conducted by Columbia University’s Earth Institute and the Mailman School of Public Health indicats that "temperature-related deaths in Manhattan could rise 20% by the 2020s and, under worst-case scenarios, 90% by the 2080s."[4] While operable windows are not a complete solution for the issue, the option of window operability is of high concern, when faced with the possibility of sealed, fixed windows that do not allow air flow or natural ventilation. Health departments located in urban areas across the country, including New York, recommend opening windows as means of preventing heat illness.[5]


Considerations

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Credit: Nasa/University of Hawaii at Manoa, Benedicte Dousset

Preventing children from falling out of open windows is also of great concern when considering operable windows. Proper window guards should be in place to ensure children cannot accidentally or intentionally fall through openings.

Operable windows are a design aspect that should be considered for critical facilities that act as refuge during extreme weather events, such as hospitals,firehouse, police stations, and emergency resource centers.


Applications


Preventing windows falls and providing ventilation from operable windows are not mutually exclusive design choices. There are several options, which take both risks into consideration. Basic guidelines to these strategies include:

  • Determining the location or the size of the window which places the opening above a reachable height for children. Standards stipulation that window openings can safely reside above 42". This allows the options of locating windows at higher than 42" above floor level, or locking lower sashes of double hung windows while allowing operability on upper portions.
  • Considering newer window designs may have operability built into the unit, such as "trickle vent" or operable louver openings. [6]

Additional Resources:

http://www.urbangreencouncil.org/servlet/servlet.FileDownload?file=015U0000001Ex4n
http://www2.buildinggreen.com/blogs/resilient-design-natural-cooling
http://www.homeenergy.org/show/article/nav/roofandattic/page/4/id/1220
http://www.good.is/posts/why-we-need-to-redesign-hospitals-for-resilience
http://windows.lbl.gov/pub/selectingwindows/window.pdf

References


  1. ^ Urban Green Council, comp. Building Resiliency Task Force. Rep. New York City: n.p., 2012.http://www.urbangreencouncil.org/servlet/servlet.FileDownload?file=015U0000001Eybd
  2. ^ New York City Department of Health and Mental Hygiene, Health Advisory #11 Heat-Related Morbidity and Mortality in New York City, May 26, 2011.
  3. ^





    Urban Green Council, comp. Building Resiliency Task Force. Rep. New York City: n.p., 2012.http://www.urbangreencouncil.org/servlet/servlet.FileDownload?file=015U0000001Eybd
  4. ^

    Freeman Klopott, Manhattan Heat Deaths Seen Rising in 2020s as Climate Warm, BLOOMBERG, May 19, 2013, http://www.bloomberg.com/news/2013-05-19/manhattan-heat-deaths-seen-rising-20-in-2020s-as-climate-warms.html.
  5. ^ http://www.nyc.gov/html/doh/html/environmental/heat-illness.shtml
  6. ^ Urban Green Council, comp. Building Resiliency Task Force. Rep. New York City: n.p., 2012.http://www.urbangreencouncil.org/servlet/servlet.FileDownload?file=015U0000001Eybd