Infection Control in Construction

Clark Buttner - Registered Architect

Senior Staff Engineer

Design and Construction Department

The University Hospital

Cincinnati, Ohio

Presentation Topics

Fundamentals of Building Air Distribution

*

Using Air Pressure to Isolate Construction Sites

Heat Transfer

Conduction is commonly the transfer of energy through the interior of a substance. For example, if you apply heat to one side of a piece of metal, soon the other side will become hot. Conduction also happens when two different substances come in contact. Consider for example your coffee spoon heating up from contact with the hot coffee in your cup. Conduction is most effective in solids-but it can happen in fluids. Have you ever noticed that metals tend to feel cold? Believe it or not, they are not colder! They only feel colder because they effectively conduct heat away from your hand. You perceive the heat that is leaving your hand as cold.

Radiation: Electromagnetic waves that directly transport heat energy through space. Sunlight is a spectrum of electromagnetic waves that radiate through space to warm our planet without the aid of direct contact as in conduction. Sunlight is changed to heat when it contacts the surface of our planet. Infrared light is another electromagnetic spectrum that generates heat on contact with a substance. Consider standing in front of a fire on a cold night. The heat you feel is radiated directly from the fire.

Convection is the transfer of heat by the actual movement of a heated medium. Heat leaves your coffee cup as the mediums of steam and air rise. Convection is the transfer of heat energy in a gas or liquid by movement of those mediums. The heat moves with the medium. Convection is the Heat Transfer mode used most frequently to heat buildings. The heat is transferred to air and the air is moved to a cold space to heat the space.

HVAC System Configurations

VAV Systems Induction Systems Convection Systems Dedicated Outdoor Systems Split Systems

Duct Systems - Concept

VAV Systems

During the 1970’s variable air volume (VAV) systems gained their current popularity. They are designed to supply only the volume of conditioned air to a space that is needed to satisfy the load. Fan energy is saved when the volume of air handled by the fan is reduced. Air volume control is accomplished by installing modulating dampers, or in some cases, an air valve, in the supply duct to each zone. As the room temperature demand becomes satisfied, the thermostat signals the damper to move the supply air zone valve toward the closed position.

A key component in the VAV system is the air valve. It is commonly installed inside an insulated sheet metal box suspended in a ceiling plenum. The air valve has a damper that regulates the air flow in response to the room's thermostat. A multi-port pressure sensing ring provides both accurate airflow sensing and control in response to duct static pressure.

When zone valves are throttled, the static pressure in the supply duct changes. A static pressure sensor located in the supply duct senses the static pressure change, and either increases or decreases the airflow from the source, using variable speed control or dampers on the main air supply fan.

As VAV systems have evolved, so have the terminals. There are six popular VAV systems. They are: Shutoff VAV Reheat Parallel Fan Powered Series Fan Powered Dual Duct Changeover/Bypass

VAV Reheat Schematic

Air Handling Unit

Dual Duct System

Single Duct System Schematic

Diffusers

Performance Data - 24 x 24 / 600 x 600 Face Size  

Listed Size

Neck Velocity (fpm)Velocity Pressure, in w.g.

400.010

500.016

600.022

700.031

800.040

900.050

1000.062

1200.090

1400.122

1600.160

6Total PressureFlow Rate, cfmNCThrow 150, 100, 50

.01578--

1-2-4

.02398--

1-2-4

.034118--

2-3-5

.046137--

2-3-6

.060157--

2-4-7

.07617619

3-4-7

.09419622

3-4-7

.13523528

4-5-8

.18327433

4-6-9

.23931437

5-7-9

8Total PressureFlow Rate, cfmNCThrow 150, 100, 50

.016140--

2-2-5

.025175--

2-3-6

.037209--

2-4-7

.050244--

3-4-8

.06527919

3-5-9

.08231422

4-6-9

.10234926

4-6-10

.14641931

5-7-11

.19948936

6-8-12

.26055840

7-9-12

Air Movement

FPM vs CFM

FPM: Feet per Minute, a rate or speed

CFM: Cubic Feet per Minute, a rate of volume

CFM must be divided by the cross sectional area of the duct in order to find FPM

A duct carrying 400 cfm that has a dimension of 6”x8” will have a FPM of: 400 x .5’ x .66’ = 132

Pressure Differential

New Buildings

New building construction presents some risk to hospital patients. Protective measures during construction adjacent to existing facilities can include:

•Exterior pre-filters

•Internal pre-filters

•Reduce air infiltration

•Building pressurization

•Building recirculation daytime

•Redefine patient pathways

•Dust Sampling

•Reduce dust generation through wetting

•Monitor demolition and/or excavation

•Monitor wind and weather

Abatement Technologies HEPA Fan Models HEPA-AIRE® Model H600V - At just 46 lbs., including filters, the H600V is our most lightweight and portable

model. It is ideally suited for use in confined spaces, where space is limited. This “mighty mite” is designed to produce up to 600 cfm, yet draws only about 1.9 operating amps. Features include two top handles, an attached 8 in. outlet collar and plastic feet to protect surfaces. Available options include a drop-in caster cart and an inlet manifold that accepts 8” inlet ducting.

Variable speed controller (50-600 cfm) Filter change indicator light Maintenance-free motorized impeller Internally protected, 99.97% certified HEPA filter HEPA-AIRE® Model H1000V - The compact, full-feature H1000V is a smaller and more mobile option to 2,000 cfm

machines. It is ideal for jobs requiring a higher level of portability and maneuverability, such as residential mold remediation. Features include a polished aluminum cabinet, professional, high-tech appearance and all the ‘bells and whistles’. The fully variable speed controller (100-900 cfm) enables the user to "tune in" airflow to meet specific job requirements.

Solid rivet aircraft construction Modular, recessed control panel Tested & certified 99.97% HEPA filter Filter change indicator light Weighs just 79 lbs. HEPA-AIRE® Model H1990HP - The H1990HP provides a lighter (142 lbs.) and narrower option to full-size 2,000

cfm models. It is equipped with the same 1.75-hp, 2-speed motor as the full-size 2000 models, and its peak airflow of 1,800 cfm is only 10% less.

High capacity fiberboard HEPA tested at 1,800 cfm Deluxe, recessed control panel Thermal overload protection

HEPA Fans

Pressure and Measurement

Environment of Care

Standard EC.5.50The hospital develops and implements activities to protect occupants during periods when a building does not meet the applicable provisions of the Life Safety Code®.Note: This standard does not apply to facilities classified as a business occupancy by the LSC.Rationale for EC.5.50When building code deficiencies are identified and cannot be immediately corrected or during renovation or construction activities, the safety of patients, staff, and other people coming to the hospital’s facilities is diminished. Hospitals need to proactively identify administrative actions (for example, additional training, additional inspections, additional fire drills, and so on) to be taken ifthese scenarios arise.Elements of Performance for EC.5.501. Each hospital develops a policy for using interim life safety measures (ILSMs).2. The policy includes written criteria for evaluating various deficiencies and construction hazards to determine when and to what extent one or more of the following measures apply:* Ensuring free and unobstructed exits. Staff receives additional information/communication when alternative exits are designated. Buildings or areas under construction must maintain escape routes for construction workers at all times, and the means ofexiting construction areas are inspected daily.* Ensuring free and unobstructed access to emergency services and for fire, police, and other emergency forces* Ensuring that fire alarm, detection, and suppression systems are in good working order. A temporary but equivalent system must be provided when any fire system is impaired. Temporary systems must be inspected and tested monthly.** Ensuring that temporary construction partitions are smoke-tight and built of noncombustible or limited combustible materials that will not contribute to the development or spread of fire* Providing additional fire-fighting equipment and training staff in its use* Prohibiting smoking throughout the hospital’s buildings and in and near construction areas* Developing and enforcing storage, housekeeping, and debris-removal practices that reduce the building’s flammable and combustible fire load to the lowest feasible level* Conducting a minimum of two fire drills per shift per quarter* Increasing surveillance of buildings, grounds, and equipment, with special attention to excavations, construction areas, construction storage, and field offices* Training staff to compensate for impaired structural or compartmentalization features of fire safety* Conducting hospitalwide safety education programs to promote awareness of fire safety building deficiencies, construction hazards, and ILSMs3. Each hospital implements ILSMs as defined in its policy.

HEPA Tent Enclosure

Construction Barriers

Barrier Type 1

Barrier Type 2

Barrier Type 3

Barrier Type 4

Date Approved

RATING / EGRESS LEGEND

SMOKE BARRIER

3HR FIRE BARRIER WALL

2HR FIRE BARRIER WALL

1 HR FIRE BARRIER WALL

2 HR FIRE BARRIER WALLAND SMOKE BARRIER

UNIVERSITY OF CINCINNATIMEGA-BLOCK 3 HR FIRE SEPARATION AND SMOKEBARRIER

SMOKE TIGHT PARTITION

EXIT

HORIZONTAL EXIT

FIRE DOOR

SMOKE DOOR

EXIT STAIR

F

S

F

F

S

S

S

S

F

S

SSS

SSS

F

F

S

S

F

F

FF

F

F

F

F

F

F

NOTE: UNIVERSITY OF CINCINNATI 'MEGA-BLOCK" 3 HR FIRE SEPARATION AND SMOKE BARRIER

S

F

S

S

F

F

F

F

FF1202AFWP

10/4/06 J.H.

Architectural Fire Wall Plan

Site Details

Infection Control in Construction