Views and Operable Windows

Why Incorporate Views and Operable Windows?

Indoor environments impact occupant well-being and productivity. Aspects of the indoor environment such as access to views and natural light, connection to nature, and personal control over environmental conditions all play a role in occupant comfort (see Individual Comfort Controls).[1] Access to views of the outside contributes to occupant well-being.[2] Many studies have found that people value daylight and prefer to be near windows, and there is an increasing understanding that being near a window can be psychologically and physiologically beneficial, mainly if views contain natural features. Visual contact with nature through window views enhances mood, reduces stress, and promotes a higher quality of life (see Biophilic Design).[3] A study by Roger Ulrich compared postoperative recovery rates of patients experiencing similar surgical procedures but having different window views of trees and a lake, no window views, or a view of a brick wall. The study found that the window view patients recovered significantly faster, required less pharmaceutical assistance, and had fewer post-operative complications, supporting the idea that enhanced opportunities for emotionally bonding with nature promote feelings of calm, confidence, and personal well-being.[4]

Operable windows can increase occupant comfort and provide psychological benefits through natural ventilation, connection to natural elements and individual control over the indoor environment (see Natural Ventilation). Operable windows can also contribute to improved indoor air quality, depending on the quality of the outdoor air. Monitor outdoor air quality through resources such as the US EPA “Air Now” online tool (airnow.gov) that lists air quality conditions by zip code.[5]

One study compared naturally ventilated buildings (i.e., occupant-controlled operable windows) with centrally controlled HVAC systems (in which occupants had no control over their environment) found that occupants in the naturally ventilated buildings accepted a full range of temperatures compared to occupants who did not have operable windows. One hypothesis for this finding is that occupants with greater control over the indoor environment have a higher tolerance of temperature range.[6]

Figure 1 – Office with operable windows and view of trees (Source: Flickr drewsaunders http://www.flickr.com/photos/drewbsaunders/116533602/ ).

How to Incorporate Views and Operable Windows

The factors that define indoor environmental quality connect directly to each other. For example, the decision about the placement or type of window can impact access to natural light, connection to the outdoors, acoustics, thermal comfort, occupant control, and air quality (see Windows and Skylights).[7] It is essential to consider all of these components in the design phase of a project. There are many resources available regarding design steps to consider for the placement of operable windows and to optimize views (see Resources section). Incorporating views and operable windows in existing buildings involves complex interactions among multiple building systems and disciplines, requiring an integrated design process. Renovations provide an opportunity to assess current views and window performance and to identify opportunities for improvement.

Although there are many benefits associated with operable windows, they can also increase the threat of water and air leakage without careful window selection, design, and installation (see Air Infiltration Reduction). Operable windows can also increase noise and airborne pollutants in the interior space and make it harder to control thermal comfort with various types of HVAC systems (see Acoustic Comfort). Facilities staff and building occupants should be aware of the limitations and issues that can arise from operable window use and methods to mitigate these issues (see Resources).[8]

Examples

AtlantiCare – The Cancer Institute, Egg Harbor Township, NJ.

AtlantiCare designed and constructed its new Cancer Care Institute according to US Green Building Council LEED standards, achieving LEED Gold certification. The Cancer Institute was the first AtlantiCare building to achieve LEED certification.

Highlights include:

• Natural lighting including an automatic light-monitoring system to reduce electricity usage.
• The facility features a natural theme, incorporating a healing arts program.
• Nature has been brought inside and trees are planted in several areas inside the facility.
• Three-quarters of the interior space provides natural daylight through the glass façade, skylights and large windows throughout the building.

The Herman Miller Building, Holland, Michigan.

Although people prefer being in windowed rather than windowless spaces, the view itself has consequences for well-being. Studies have found that views of nature are especially beneficial and reduce stress, provide mental relief, improve the perceived quality of life, and improve emotional functioning. A case study of the Herman Miller building in Holland, Michigan, shows improvements in social functioning and sense of belonging associated with including break areas; a centrally located cafeteria; an interior, daylit and tree-lined “street”; and high levels of internal glazing that offered views into the street and interior spaces.[9]

Benefits

Incorporating views and operable windows:

• Enhances occupant comfort and health
• Increases occupant satisfaction
• Increases productivity[10]
• Offers natural ventilation[11]
• Increases access to daylight and window views which can improve psychological functioning and well-being of occupants
• Reduces stress and promotes positive emotional states and may also influence cognitive functioning[12]

Costs

The cost of incorporating operable windows and maximizing views from interior spaces vary by project, and these aspects should be considered early in the window upgrade phase to optimize cost efficiencies. Operable windows are generally more expensive than static windows. Expect to pay approximately 20-percent more for fully operable windows vs. fixed windows. Price also changes by type of operable window – sliders are cheaper than casements, for example. Many factors affect cost and designers need to think holistically about the project. Operable windows can be used to offset mechanical ventilation costs and can allow for downsizing fans (see Properly-Sized, High-Performance HVAC Equipment and Controls). Installing a traditional mechanical HVAC unit on the roof and installing operable windows can lead to inefficiencies in running the system if occupants are not adequately aware of how the building systems function.[13]

Resiliency

In the event of a fire or other emergency in the building, operable windows (depending on their size) can act as a point of egress for occupants and can also serve as an access point for firefighters and their lifesaving equipment, especially if any other exits are blocked off and inaccessible to the building’s occupants. Operable windows can also help provide natural ventilation and thermal comfort during a power outage.[14]

[1] Whole Building Design Guide. Promote Health and Well Being http://www.wbdg.org/design-objectives/productive/promote-health-well-being  (accessed January 12, 2019).

[2] GSA. Sustainable Facilities Tool. Occupant Comfort. http://www.wbdg.org/design-objectives/productive/promote-health-well-being (accessed January 12, 2019).

[3] Judith H. Heerwagen, Ph.D. Green Buildings, Organizational Success, and Occupant Productivity. Whole Building Design Guide. https://www.wbdg.org/files/pdfs/grn_bldgs_org_success.pdf (accessed September 20, 2018).

[4] Ulrich, Roger S. View Through a Window May Influence Recovery from Surgery. The Center for Health Design. https://www.healthdesign.org/sites/default/files/article-pdfs/Ulrich-1984-CHD-KPS.pdf  (accessed September 20, 2018).

[5] US EPA. AirNow. https://www.airnow.gov (accessed December 12, 2018).

[6] ASHRAE. http://www.cbe.berkeley.edu/research/pdf_files/Brager2004_OpWindows_Trans.pdf (accessed September 20, 2018)

[7] California Sustainable Design Training. IEQ. https://www.calrecycle.ca.gov/docs/cr/GreenBuilding/Training/StateManual/StateManual.pdf  (accessed September 20, 2018).

[8] Buildings.com “A Breath of Fresh Air.” http://www.buildings.com/ArticleDetails/tabid/3321/ArticleID/2749/Default.aspx (accessed January 12, 2019).

[9] The American Institute of Architects (AIA). www.aiatopten.org/node/169 (accessed September 20, 2018)

[10] California Sustainable Design Training. IEQ. https://www.calrecycle.ca.gov/docs/cr/GreenBuilding/Training/StateManual/StateManual.pdf  (accessed September 20, 2018).

[11] Buildings.com   “A Breath of Fresh Air.” http://www.buildings.com/ArticleDetails/tabid/3321/ArticleID/2749/Default.aspx (accessed September 20, 2018).

[12] Judith H. Heerwagen, Ph.D. Green Buildings, Organizational Success, and Occupant Productivity. Whole Building Design Guide. https://www.wbdg.org/files/pdfs/grn_bldgs_org_success.pdf (accessed September 20, 2018).

[13] Buildings. “A Breath of Fresh Air.” http://www.buildings.com/ArticleDetails/tabid/3321/ArticleID/2749/Default.aspx (accessed January 12, 2019)

[14] Building Green. Resilient Design: Natural Cooling. https://www.buildinggreen.com/blog/resilient-design-natural-cooling (accessed January 12, 2019).