Out-Patient Facilities


Out-Patient Facility

Outpatient surgical facilities and medical buildings typically operate only 8 to 12 hours a day. Some are essentially medical office/clinic settings, while others might require hospital design standards. In any case, many are associated with and adjacent to specific hospitals.

Many outpatient facilities require tenants to facilitate and pay for their own utilities. This requirement influences many decisions about the facility including construction, lighting, and HVAC.


Typical System

Roof Top HVAC

Most of these facilities are low-rise and are typically designed with multiple unitary systems that use roof-top heating and cooling units, one per zone. This is particularly necessary if occupancy hours vary. Loads can vary widely and must be able to quickly switch from heating to cooling, thus requiring automatic, simple-to-operate controls. Special purpose spaces, such as laboratories and surgical suites, may require separate designs.

Provision should be made to shut outdoor air dampers when individual zones or stores are unoccupied. Many places have stringent codes regarding fire, smoke, building design, ventilation, and noise control. In many cases, noise production and protection from vandalism must be considered. As an alternative to roof-top equipment, geothermal heat-pump systems are becoming more popular, because they have no outdoor equipment to create noise or get damaged.

Surgical Suites

Cleaning Operating Room

Larger, out-patient facilities include operating rooms and surgical suites that are considered clean rooms. Their primary concern is limiting particle and microbial contamination. Within a clinic, no area requires more care in preserving an aseptic environment.

Air distribution should occur via a ceiling delivery system that flows down through several exhaust vents located  no less than 3 inches above the floor on opposite walls. Avoid high induction diffusers, and be sure to maintain positive pressure within the room. ASHRAE ventilation Standard 62-1989 mandates a maximum occupancy of 20 people per 1000 sq ft and well-circulated, fresh air from outdoors should be no less than 30 cfm per person at all times. A minimum of 15 total air changes per hour is recommended, however 100 percent outdoor air should be limited to those cases where codes require it and only if heat recovery devices are used. All air should be exhausted and not recirculated within the room.

Operating rooms are typically not in use more than 8 to 12 hours per day, except in emergencies, and there should be a way to reduce airflow when it is unoccupied. However, to ensure sterile conditions, this may not always be possible, because it may otherwise be difficult to maintain positive pressure continuously. Additional recommended practices for operating rooms include:

  • Variable temperature control ranging from 68 to 76°F, relative humidity in the 50% to 60% range, and excess air available to ensure positive air pressure in adjoining rooms
  • All room openings should be well sealed
  • Maintain staged filter efficiencies of 25% in filter bed No. 1 and 90% in filter bed No. 2, plus 99.97% HEPA filters at all air outlets
  • Acoustic materials should not be used as duct linings unless at least 90% minimum efficiency filters are used downstream of the linings
  • Any sprayed-in insulation and fireproofing should be treated with fungi growth inhibitor
  • Sufficient lengths of watertight stainless steel duct should be installed downstream of humidification equipment to ensure complete evaporation before the air enters a room

A separate, dedicated, air-cooled refrigeration facility able to perform in low, ambient temperature conditions is recommended since operating rooms are in use year round, often at odd hours, and equipped with an emergency power generator unit.


  • Old and/or inefficient systems should be investigated for upgrading or replacement opportunities, particularly if CFC refrigerants are used
  • Where demand and/or on-peak energy costs are high, look into thermal storage
  • Desiccant and/or heat pipes should be added to air makeup systems
  • Energy conservation concepts discussed above that are not currently implemented, or antiquated, or inappropriate control systems all represent energy saving opportunities

Water Heating


Typical System

Water heating is not a major energy user with application typically limited to hand washing and general cleaning purposes. Most water heating is done separately from the building heating system and uses direct resistance or gas heaters; in some cases, point-of-use heaters. Some high-quality buildings use central distribution systems with storage and constant recirculation where it is desirable to have hot water available continuously at the fixtures. If multiple tenants occupy the building, then individual storage heaters for each tenant space are often used.


If existing systems are inefficient or inadequate, they should be replaced with modern, more efficient equipment as soon as possible. If a source of excess/waste heat (i.e. tower water) is available, consider a water-to-water heat-pump heater.


As outpatient and therapy facilities occupy the greatest percentage of space in hospitals, greater emphasis is placed on their design. They must be functional and, at the same time, comfortable to live in. Lighting should help support the healing process. It is recommended that approximately 20 to 50 footcandles of lighting be provided in physical, occupational, and inhalation therapy areas. Radiation therapy light levels should be approximately 5 to 10 footcandles. Dialysis areas need 100 to 200 footcandles.

Choose lamp sources with a color temperature of 3500k to 4100k and at least 80 CRI for maximum comfort and utility. Triphosphor fluorescent and compact fluorescent lights are both good choices.

If there are monitors or VDT screens in the area, choose low glare, high VCP fluorescent fixtures. Indirect fluorescent lighting may also be appropriate, especially in dialysis units where patients face the ceiling for several hours.


Exit SignIncandescent and fluorescent exit signs should be replaced with LED exit signs. T-12 fluorescent lamps with magnetic ballasts should be replaced with T-8 lamps with electronic ballasts. Make sure that the electronic ballast selected is compatible with any sensitive medical equipment.

Parking lot, security, and façade lighting may contain incandescent and mercury vapor lamps. These should be replaced with metal halide systems: high pressure sodium is frequently uncomfortable for doctors due to the color.

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