I N T ERI OR S
The importance of surface reflectivity
Daylighting depends on both the light received directly from To take advantage of available daylighting, electric lighting
the sky and light reflected from interior surfaces. Patient should be designed and controlled either by dimming, or by
rooms with high internal reflectivity will have more light at the switching off completely. A light sensor and continuous or step
back of the room and more even light distribution. Minimum dimmer can maintain ambient illumination levels at a constant
reflectivities should be: ceiling, 90 percent; walls, 70 percent; value, based on the amount of daylight in the space.
floors, 40 percent; and furniture and equipment, 70 percent;
As sky conditions change, automatic, dimmable, indirect
to allow daylight to reflect off these surfaces and penetrate
lighting luminaires make an unnoticeable transition from
further into the room.
electric lighting to daylighting and back.
Daylighting integration with electric lighting
Patient control of daylighting
Task-ambient electric lighting design strategies work well with
The ability to manipulate the environment, including bedside
daylighting because room ambient light levels, lower than task
control of lighting and window shades, contributes to a patient’s
lighting requirements, are easy to meet with daylight. Ambient
psychological outlook, rate of healing, and quality of stay.3
daylight should be supplemented with task electric lighting to
increase lighting levels where specific tasks are performed.
1 2 3
Ulrich, R.S., “How Design Impacts Wellness,” Healthcare Devlin, A.S. and Arrneill, A., Health Care Environments and Ulrich, p.23
Forum Journal, September–October 1992, vol. 35, pp. 20-25 Patient Outcomes: A Review of the Literature,” Environment
and Behavior, September 2003, vol. 35, num. 5, pp. 665-694
DAY L IGHT I NG HOSPI TA L PAT I EN T ROOMS
A Summary of a Joint Research Study
What is a daylit patient room? Will daylighting save energy?
A daylit patient room uses light from the sky for daytime When daylighting is used to reduce ambient electric lighting,
illumination, effectively reducing the need for electric light. lighting energy savings during daylight hours can be as high
The amount of daylight that comes into a room depends as 87 percent.
Legacy Salmon Creek Hospital upon the area and location of the window and the amount
of the sky the window “sees.” The distribution of that Can it reduce the mechanical system size and cost?
light is a function of the window’s shape and location in Daylighting provides more illumination per watt than electric
This is a brief summary of conclusions from Daylighing Patient Funding for this document and for Daylighting Patient Rooms the window wall and the proportions of the room, room lighting and therefore less heat. When combined with a
Rooms in Northwest Hospitals, a 2005 study jointly undertaken in Northwest Hospitals was provided by the BetterBricks reflectivity, and obstructions within the space. task-ambient lighting strategy that only puts light where it is
by the Energy Studies in Buildings Laboratory, Department program, the commercial buildings initiative of the Northwest needed, daylighting results in significantly less heat gain in a
of Architecture, University of Oregon (G.Z. Brown, Jeff Energy Efficiency Alliance. Supported by local electric utilities, Does it cost anything to daylight a patient room? room than typical electric lighting alternatives, reducing the
Kline, Gina Livingston, Brooks McDonald, Crawford Smith, BetterBricks advocates for changes to energy-related business If the hospital construction budget includes adequate cooling load and the size and cost of the HVAC system.
Mark Wilkerson) and Zimmer Gunsul Frasca Architects LLP practices in Northwest buildings. window area, shades, and electric lights, only a control to
(Johanna Brickman, David Staczek). turn off the lights, when daylight is available, must be added Can daylighting improve patient well-being?
(a short payback). The first cost of the patient room can be A patient room providing good outdoor views and daylighting
reduced if the design of the room’s structural, mechanical, can increase patient well-being: a psychological state resulting
and daylight systems are considered together to lower the in reduced stress and anxiety, lower blood pressure, improved
floor-to-floor height, while increasing ceiling height and post-operative recovery, reduced need for pain medication,
Energy Studies in Buildings Laboratory improving daylighting. and shorter hospital stays.1
University of Oregon
DESIGN I NG T HE DAY L I T PAT I EN T ROOM Daylight and view window differences
Daylight and view windows, in patient rooms, have different
and sometimes conflicting requirements, and the most
straightforward design resolution is to separate these two
windows and their functions.
A Positioning the toilet room B
Outboard toilet rooms, placed along the exterior wall, greatly D The daylight window provides ambient light.
reduce daylighting potential. For maximum daylighting benefit,
E The view window, while also admitting light into the room,
toilet rooms should be located between two adjacent patient
functions primarily as the patient’s view to the outside, relieving
rooms, or placed inboard, adjacent to the interior corridor.
stress, promoting relaxation, and even preventing delirium.2
The daylight window should be located with its head height as
high as possible in the wall and should extend the full width of
D the room.
Outboard Shared wall Inboard
The view window should be sized and placed to allow views
E from the patient’s bed and, to reduce glare, should be shaded
F or of low visible light transmittance.
B Room depth
F There are two approaches to sizing the daylight window.
The depth of the hospital room that
can be usefully daylit is dependent on The first optimizes the size of the window for both daylighting
the size and head height of the and thermal performance. The second sizes the window for
daylight window. In our studies, maximum daylighting performance and uses shades,
adequately daylit patient rooms, with light shelves and louvers to adjust its size, as needed, to
inboard or shared toilets, ranged from maintain the best thermal performance, as conditions change.
13 feet to 19 feet deep. Shallower
rooms are most desirable, because Glazing specifications
they facilitate more even daylight Daylight windows should, ideally, have low u-values, low
distribution to the back of the room. solar heat gain coefficients (SHGC), and high visible light
transmission (VLT). Depending upon the climate and a room’s
C Ceiling configuration and HVAC duct location aperture control capabilities, either the R-value or SHGC
Higher ceilings allow higher windows and deeper daylight A may be relatively more important. Because they are not used
penetration. An angled ceiling, sloping down from the for daylighting, view windows can have a lower visual light
bottom of the structure at the outboard wall to the nominal transmission and therefore, lower u-values and lower SHGC.
ceiling height at the inboard wall (achieved by moving ducts
away from the perimeter toward the corridor side of the room), The best window wall configurations
will allow a higher window head height. In plan, an angled window wall can have a different orientation
than the rest of the building and potentially achieve better
Typical hospital patient rooms place a supply duct along the building
daylighting performance. If the window wall is notched, or is
perimeter to offset drafts from glazing. High performance glazing
designed with a corner window, the view window can have a
allows the use of systems that can be located away from the exterior
different orientation than the daylight window.
window, providing greater design flexibility for the integration of ceilings
with daylight window head heights, within a given floor-to-floor height.
15’ 0” 12’ 6” 12’ 0”
Flat ceiling; typical Stepped ceiling; steel Sloped ceiling;
steel structure structure; upturned beam concrete structure Angled window wall Notched window wall