1、Special Design Considerations for Institutional and Correctional Facilities Richard E. Vehlow, PE Member ASHRAE ABSTRACT This paper will provide the Owner, Design Engineer, Contractors, and local & State Authorities with the information regarding the design criteria they need in order to provide ins
2、pections, permitting, adequate equipment sizing, temperature control, energy savings, testing & balancing, and commissioning of various types of justice facilities. We will discuss institutional and correctional facilities in this Conference paper. INTRODUCTION Justice Facilities require an extra me
3、asure of care in design and adherence to codes due to the volatility and security of the interior environment. Given various general concepts on security and codes governing these special classifications of inhabited facilities, special considerations must be given to air movement systems, steam and
4、 hot water heating, environmental control, layout of facility-wide mechanical systems, green design, seismic issues, hazardous material abatement, and other project conditions. This paper will provide an overview of each of the important components of compliant designs that would adequately serve in
5、stitutional classifications of facilities. GENERAL SECURITY CONCEPTS Inmates of correctional institutions, rehabilitation camps and other secure facilities are considered to be wards of the government entity in charge of the specific facility. For purposes of simplicity and familiarity, the focus sh
6、all be on state-level facilities, hence the term “wards of the state” applies. A ward of the state must have his or her needs and comfort satisfactorally addressed by the state in charge of the facility. In terms of security, providing a safe and secure environment serves to avoid bodily harm for wh
7、ich the state may be liable, or damages to the facility and systems which may be costly to replace. From an HVAC standpoint, certain basic design practices must be adhered to whenever possible to maintain a safe and secure environment for inmates, staff and equipment. Systems must be segregated from
8、 inmate population by appropriate locked rooms, fenced areas or other partitions. Accessories, piping, fixtures and ductwork must be robust enough to withstand abuse or tampering. Fixtures and registers must be designed to avoid prisoner suicide by hanging. Cabinets and exposed equipment must be ade
9、quately sealed to avoid concealment of weapons or contraband. Exposed items, especially metal or glass, must be strong enough to withstand segments or LV-11-C060486 ASHRAE Transactions2011. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in
10、 ASHRAE Transactions, Volume 117, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAES prior written permission.shards broken off to be used as makeshift tools or weapons. Access to areas for maintenanc
11、e purposes must be made secure, and controls are to be operable by officers, maintenance personnel and administration only. System alarms should be readily seen by key or pertinent personnel and access easy enough for repairs or immediate corrections to be made to avoid emergency situations. AIRSIDE
12、 DESIGN CONSIDERATIONS Codes and best practices determine the ideal amount of fresh air that needs to be mechanically supplied to these inhabitants in close quarters. From the 2007 International Mechanical Code, some applicable airflow rates for fresh air in institutional occupancies are as follows:
13、 Occupancy/Use Estimated max occupant load (persons/1000 sf) Outdoor Air (cfm/person) Cells (with or without plumbing) 20 20 Dining Hallss 100 15Guard Stationss 40 15A standard inmate cell is required to be 80 square feet by ACA (American Correctional Association) standards. Double-bunking may occas
14、ionally be needed when large-scale renovation is in progress, therefore some cells may need to have a minimum of 40 CFM outside air supply in order to meet code. Suggestion is to size ductwork to carry 40 CFM to allow flexibility in double-bunking, if needed, and use of secure face-adjustable volume
15、 dampers to control individual cell airflow to desired air balancing. If 4 airchanges per hour are desired for an 80 square foot cell with a 9 foot ceiling, often a popular design metric for occupied spaces, then 50 CFM as a minimum would accomplish that. A duct cross section of 6” x 6” at each cell
16、 would reduce duct static pressure thus saving on fan power and eliminating much duct noise and drafts. An inmate cell is exceptionally close quarters and any duct register or diffuser would be within easy access to the inmate. Therefore inmate secure diffusers and registers must have security-grade
17、 face coverings. Typical accepted coverings are 12-gauge steel with 3/8” round or square openings on 5/8” centers. Small holes defeat the ability for the inmate to conceal contraband or makeshift weapons, however periodic inspection would still be necessary. In addition, small holes and additional v
18、anes inside register also defeat the ability to thread strings or sheet through the holes for use as nooses in suicide attempts. Another way to minimize suicide risk as well as to promote good temperature mixture is to locate the outlet on the wall at a low-to-medium height from the floor (up to 4).
19、 The usage of pick-proof security sealant such as cold-applied chemically-curing 2011 ASHRAE 487elastomeric polyurethane at the edge of the register face with the wall surface further avoids the ability to use the face as a means for concealment of illicit items. Different types of sealant are avail
20、able for wet or dry locations. An example of a standard secure register detail is shown. It should be noted on the drawing that “CC” is Construction Contractor, “ISR” is Inmate Supply Register, “IRR” is Inmate Return Register and “IER” is Inmate Exhaust Register. For optimum performance of a duct ne
21、twork in an institutional environment, especially with regards to inmate cells, good register balancing is paramount. Face-adjustable opposed-blade dampers allow for good balancing. When balancing as part of the contract, or as periodic maintenance, ensure inmate items such as cloth, cardboard and t
22、oothpaste are not in or in front of registers. Balancing operators and fasteners should be of tamper-resistant design, operable by special tools only. Ductwork poses special security and design challenges also. Standard sheet metal ductwork should always be inaccessible to inmates. Despite general f
23、ire-resistant prison construction (steel, concrete and concrete masonry units), UL-approved firestopping systems should always be used when ductwork breeches a fire-rated partition. Typical fire-ratings in a correctional facility may range among 1, 1.5, 2 or 3 hours. Partitions also usually denote b
24、oundaries of desired secure zones, so combination fire dampers and security barriers are often desired. Standard practice is often to employ the use of a security barrier when a duct with dimension of 8” or greater on a side or 48 square inches in total cross-section area penetrates a secure wall. S
25、ecurity barriers often consist of crossbars of sufficient thickness and anchoring/fastening to the duct sleeve to render the penetration impassable to anyone regardless of body size. Design examples would be a vertical ” round steel bar(s) 6” on-center welded to 10-gauge steel sleeve surrounding duc
26、t and opening. When duct height is 12” or greater, use horizontal 488 ASHRAE Transactions3/8” x 2” flat steel bar(s), also welded to sleeve. Design allows for security at minimal pressure loss for airflow. A typical combination fire damper and security barrier detail is shown. Although mixed air wit
27、h the outside air component being at or above code may be desirable in many occupancies to conserve energy, mixing outside with return air is not desirable in correctional or other institutional facilities because of the higher risk of airborne infection, such as tuberculosis, in a closely-confined
28、space. For energy recovery, air-to-air heat exchangers are desired. In non-housing situations, such as education, gym or administration buildings, if any percentage of air is to be recirculated, use of HEPA filtration is highly recommended. Many older facilities have little or no mechanical ventilat
29、ion. Upgrading systems often involves creation of mechanical rooms and spaces where none were previously. Rooftop or attic systems often are feasible but would require structural analysis of existing building to determine ability to bear weight of air handlers, steel equipment stands and concrete pa
30、ds. Ducts and piping may need to be soffited, which must be done with steel for security and structural stability reasons and must be mindful of ceiling clearance and cell width dimensions (76” and 68” respectively) as set by ACA code. Equipment may need field assembly or structural engineering assi
31、stance to temporarily remove walls or windows for equipment installation. One possible solution to the structural challenges of duct retrofits is exterior duct chases. Older cells are often too narrow to allow for soffiting. In 2011 ASHRAE 489this solution, insulated ducts and piping for radiation r
32、un up sides of building from the mechanical rooms in basements or penthouses to cells on the other floors. Architectural and structural trades would assist to maintain security and create a more aesthetic, thermally resistive enclosure for risers. Exhaust air may use existing plumbing chases and mai
33、ntenance access spaces as plenums served by rooftop ventilators. WATERSIDE/STEAMSIDE DESIGN CONSIDERATIONS The typical older correctional facility bases its campuswide distribution of heat on medium to high pressure steam with conversion to low-pressure steam heating on a building-by-building basis.
34、 Powerhouse boilers typically produce medium pressure steam at 50-90 psig, which is reduced in each building to 10-15 psig before directly feeding low-pressure cast-iron steam radiators and unit heaters. Sometimes basic shell-tube heat exchangers are used in a primary-secondary loop setup. The curre
35、nt trend is to replace all-steam systems, whether single or tandem loop, with steam-to-hot water heat exchangers and finned-tube or convector radiators for better control and less noise. For a modern design, or for facilities built in the past 25 years, a primary-secondary hot water loop system is t
36、he more popular choice. Powerhouse boilers produce high-temperature water under pressure at a peak temperature of 220 to 250 degrees Fahrenheit. Heat exchangers in each building typically transfer heat from the primary side at 30 to 50 degrees Fahrenheit delta-T to the secondary side, typically at 2
37、0 degrees Fahrenheit delta-T. Secondary hot water pumps move the water to fin-tube or convector radiation. The hotter primary loop is also often used to provide heat exchange in a similar fashion separately to domestic hot water via semi-instantaneous hot water heaters. Typical leaving secondary hot
38、 water temperature for heating is 180 to 200 degrees Fahrenheit, for domestic hot water it is up to 140 degrees Fahrenheit, and for laundries or dishwashing, it is 180 degrees Fahrenheit out of a separate dedicated hot water heater or booster. In terms of layout, the latest trend is to move the unde
39、rground primary hot water loops to above-ground for maintenance purposes. Piping is suspended by concrete piers 14 to 15 feet above ground to allow for vehicle clearance and significant distance from inmates. Piping is also insulated by 3” fiberglass with a polyethylene or EPDM jacketing, not metal
40、sheeting, when inside the secure perimeter to avoid makeshift weapons from vandalized covering. A typical piping branch to a building drops to about 2 above ground near the building utility entrance and is shielded from falling ice from the roof eave. Running pipes for a short distance parallel to t
41、he exterior building wall and under the eave allows for protection from ice as well as an expansion arm for the pipe. There also should be significant consideration for seismic design enhancements on all above-ground piping structures dependent on the seismic classification of the area. Interior sec
42、urity issues ring as true for steam and hot water heating elements as they do for airside terminal devices and registers. All heating units and piping 490 ASHRAE Transactionsshould be protected by 12-gauge steel covering whenever within possible reach of inmates. Perforations of 3/8” diameter on 5/8
43、” centers is, like air diffuser and register faceplates, an ideal size to allow for the convective heat transfer and flow of air across the hot water elements while keeping out the possibility of hidden contraband or weapons or the ability to facilitate a suicide by hanging. Valves and strainers sho
44、uld be behind steel access doors secured by tamper-resistant security fasteners. Exposed piping should be insulated and located behind 12-gauge steel chases. For vertical risers, it is preferable to have a foot at the bottom and top of the riser in a certain room to be perforated similarly to the ra
45、diation covering to prevent a slow buildup of heat despite the pipe insulation. Regarding the selection and placement of radiators, it is more preferable to use convectors in lieu of regular fin-tube radiators in multi-tiered cellblocks and other large spaces, since 2000 BTUh/ft may be obtained by c
46、onvectors vs. only 1300 BTUh/ft by standard radiation. Convector units located within one foot of finished floor can provide even heat rise through gallery or clerestory. Ceiling fans in secure cages can help circulate heat risen to ceiling. CONTROLS Direct digital controls (DDC) are not in every fa
47、cility, but each new project aims, whenever possible, to phase them in. BACnet protocol is generally preferred. Initial DDC installation calls for a Primary Operators station (desktop computer) in the powerhouse and/or the Plant Superintendents office and Portable Operator terminals (laptop computer
48、s) for the maintenance staff. Subsequent projects elsewhere in the facility would require fiberoptic interconnection to existing network, usually by way of patch panels, and the programming of additional points into the system software. Software and computers should be upgraded every five to ten yea
49、rs, and network hardware specifications should be constantly updated with the latest high-end computers available and appropriate for the application. Wireless technology has yet to be harnessed for such networking. To date, care has been taken with potential interference with wireless security communication and infrared sensing. There is also the question of increased maintenance in battery recharging or replacement. However, wireless differential pressure sensing for primary hot water flow is being explored. Indeed, wireless technology would save on construction costs for fibe
