Engsysco

Wei Sun, P.E.

ASHRAE Distinguished Lecturer

Society Technology Transfer Committee Chair (12-13)

“Clean Spaces” Technical Committee (TC9.11) Chair (07-10)

“Healthcare Facilities” Technical Committee (TC9.6) Member

“Laboratory Systems” Technical Committee (TC9.10) Member

IEST (Institute of Environmental Sciences and Technology) Society President

ISO 14644 Cleanroom Standards USA Delegate

Engsysco, Inc. President

Ann Arbor, Michigan, USA

Web: www.engsysco.com Email: wsun@engsysco.com

HVAC Systems Design for

Airborne Infection Control Spaces

in Health Care Facilities Belgrade, Serbia April 28, 2017

2015 ASHRAE - Handbook Chapter 8

2013 ASHRAE - “Hospital and Clinics

HVAC Design Manual”

2010 FGI/AIA - “Guidelines for Design

and Construction of Hospital and Health

Care Facilities”

ASHRAE/ASHE Standard 170-2013 -

Ventilation of Health Care Facilities (with

addendums)

2006 CDC - “Infection Control

Guidelines”

2003 CDC - “Guidelines for

Environmental Infection Control in

Health-Care Facilities”

US Healthcare Facilities

Design Guidelines and Standards

USP <797> Guidebook to Pharmaceutical Compounding - Sterile Preparations (2008)

Unified Facilities Criteria (UFC) - Design: Medical Military Facilities (2009)

Unified Facilities Criteria (UFC) – Design Build: Technical Requirements (2005)

VA HVAC Design Manual (2008)

NIH Design Requirements Manual for Biomedical Laboratories and Animal Research Facilities (2008)

WHO Interim Guidelines - Infection Prevention and Control of Pandemic - and Epidemic-Prone Respiratory Diseases in Health Care

US Healthcare Facilities

Design Guidelines and Standards

Aerobiological Engineering Handbook - Airborne Disease Control Technologies

2012 NFPA Standard 99 - Standard for Health Care Facilities

2012 NFPA Handbook - Health Care Facilities Code Handbook

2012 IEEE, National Electrical Safety Code (NESC)

US Healthcare Facilities

Design Guidelines and Standards

Architectural Design:

2012 International Building Code

Engineering Design:

2012 International Mechanical Code

2012 International Plumbing Code

2012 International Fire Code

2012 International Energy Conservation Code

US General Building Codes

Source controls

• Patients with Tuberculosis, Chicken pox, Measles, Smallpox, SARS, Monkey pox, antibiotic resistant microbes..

• Cough etiquette and respiratory hygiene

Administrative controls

• Construction of infection control infrastructure

• Early detection, isolation, treatment and report

Personal protective equipment – primary barrier

Engineering controls – secondary barrier

• Patient placement (room layout, configuration)

• Space environmental control

Airborne Infection Risk Management An Critical Portion of Infection Control Risk Assessment (ICRA)

Operating Room (Operation Theatre)

Airborne Infection Isolation Room (AII)

Protective Environment (PE)

Critical and Intensive Care Unit

Health-Care Settings with Special Environmental

Controls for Airborne Infections (US CDC)

Function Space Standard

Basis

Pressure

Relationship

to Adjacent

Areas

Min. OA

ACH

Min.

Total

ACH

All Air

Exhausted

Directly to

Outside

Air

Recirculated

Within Room

Units (Ex. w/

HEPA)

Relative

Humidity

%

Design

Temp.

°F

Operating Room

(Re-circulating air

system)

AIA Positive 5 25 — No 45-55 62-80

ASHRAE(08) Positive 4 20 N/R No 30-60 68-75

CDC Positive 3 15 N/R Yes 30-60 68-75

Airborne infection

Isolation Room

AIA Negative 2 12 Yes No — 75

ASHRAE(08) Negative 2 12 Yes No — 70-75

CDC Negative 2 12 Yes No — 75

Isolation

Anteroom

AIA Positive or Negative

2 10 Yes No — —

ASHRAE(08) Positive or Negative

2 10 Yes No — —

CDC Positive or Negative

2 10 Yes No — —

Protective

Environment

Room

AIA Positive 2 12 — No — 75

ASHRAE(08) Positive 2 12 — No — 70-75

CDC Positive 2 12 — No — 75

Critical and

Intensive Care

AIA N/A 2 6 — No 30-60 70-75

ASHRAE(08) Positive 2 6 N/R No 30-60 70-75

CDC N/A 2 6 — No 30-60 70-75

(06)

(03)

(06)

(03)

(06)

(03)

(06)

(03)

(06)

(03)

20

Ventilation Requirements (USA)

Ventilation Requirements (ASHRAE 170 – 2013 Std)

Constant volume air handling systems are common in operating rooms, variable systems are permitted for use “only if” they continue to provide a positive room pressure (normally 0.01-0.03 in. wg or 2.5-8 Pa differential) with respect to the corridors and adjacent areas and the required ACHs are maintained.

HEPA-filtered (99.97%) laminar airflow and UVGI (Ultraviolet Germicidal Irradiation) as additional measures could reduce SSI (Surgical-Site Infection) risk for certain operations. Laminar airflow is designed to move clean air over the aseptic operating field at a uniform velocity (0.3–0.5 m/s) (60-100 fpm), sweeping away particles in its path, and recirculated air is passed through a HEPA filter.

Operating Room (1) (Example - CDC Based)

Operating Room (2)

Operating Room (3)

(ASHRAE 170-2013)

Additional diffusers may be located outside of the Primary Supply Diffuser Array (Zone) if needed to achieve required environmental conditions or air change rates, but no more than 30% of the Primary Supply Diffuser Array.

New definition of Procedure Room is equivalent to Class A ORs previously.

New definition of Operating Room is equivalent to Class B and C ORs previously.

Enlarged Clean Zone Area (3.2m x 3.2m)

Higher ACH

Foldable Air Curtain

Floor Mounted System

Airflow Effectiveness Improvement in OR

Use of negative pressure rooms with control of air flow direction (normally - 0.01 to -0.03 in. wg or -2.5 to -8 Pa differential), airflow volume differential at a minimum of 125 CFM (60 L/s) exhaust versus supply.

Seal room below 0.5 ft2 (465 cm2) of air leakage (called Effective Leakage Area under 4 Pa pressure differential test)

Filtered (90%) supply air to the room. Air from negative pressure rooms and treatment rooms is to be HEPA-filtered (99.97%) and exhausted directly to the outside. Recirculation is not allowed. Isolation rooms can be constructed ideally with an anteroom. UVGI fixtures can be placed in upper room or inside the ducts as an additional measure.

Personal protective equipment such as respirators (NIOSH type N95 or powered purifier) for healthcare workers prior to entering isolation rooms.

Airborne Infection Isolation Room (1) (Example - CDC Based)

Cascading

Sink

Bubble

Airborne Infection Isolation Room (2) (Example - CDC Based)

These rooms are to be designed for high-risk, immuno-compromised patients (BMT, organ transplant, leukemia, burn, late-stage HIV…) to minimize fungal spore counts (measured in CFU) in air.

Ideally, incoming air by HEPA filters, supply air on one side of the room across the patient, and exhaust out through the opposite side of the room.

Positive room air pressure of 2.5 Pa (0.01" w.g.) relative to the corridor, airflow volume differential at a minimum of 125 CFM (60L/s) supply versus exhaust.

Seal room below 0.5 ft2 (465 cm2) of air leakage.

Protective Environments (1) (Example - CDC Based)

Protective Environments (2)

Based on the patient type and critical-care suite configuration, positive, negative or neutral room pressure (normally from -0.01 to 0.01 in. wg or -2.5 to 2.5 Pa differential) with respect to the corridors and adjacent areas.

Filtered (90%) supply airflow, and recirculated air is allowed.

Critical and Intensive Care Room (1) (Example - CDC Based)

Critical and Intensive Care Room (2)

Hospital Room Airflow, Pressure, Flow Direction, Temperature and Humidity Requirements

(For Hospitals and Outpatient Facilities, FGI) (1)

Hospital Room Airflow, Pressure, Flow Direction, Temperature and Humidity Requirements

(For Hospitals and Outpatient Facilities, FGI) (2)

Example Design Criteria – Operating Room

Complex (multi-functional) AHU System (Discharge at 55°F year-around)

• Exhaust only

• Exhaust w./ heat pipe

• Exhaust w./ enthalpy wheel

• Dual Return paths

• 100% OA for purge

Use only with

psychrometric

analysis!!!

AHU Flow Diagram (With Possible Options)

Renewable Energy

Geothermal

Solar Panels

Wind Turbine

Energy Recovery

Cogeneration - Not only for Backup Power, but as Main Power.

Use Water-cooled Compressors (Large) to Recover Waste Heat

Energy Recovery - Heat Pipe, Thermal Wheel, Run-around Coils

Building

Building Envelope - Increase Air Tightness, Reduce Leakage through Windows and Walls, Add Vestibules

Use Vertical Fenestration and Overhang in West, East & South Windows

Reduce or Eliminate of West-side Windows

Commissioning and Retro-commissioning – User friendly Software

ASHRAE Developing Cost Effective Solutions

Toward Low Energy Healthcare Buildings

Lighting & Power

Sensor Controlled Natural Day Lighting

Building and Space (Section/zone) Metering through BMS

Reduce Plug Load: Use BMS Clock Control to Deactivate Non-Critical Office Equipment during Night/Weekends, Can Be Overridden with Light Switch.

Reduce Lighting Waste by Occupancy Sensor

LED Lights

Water

Collect Rain Water with Filtration for Irrigation and Underground Sprinkler System

Cooling Condensate Collection (AHU over 5 Ton) for Cooling Tower Make-Up Water

ASHRAE Developing Cost Effective Solutions

Toward Low Energy Healthcare Buildings

HVAC

Logic Controlled Ventilation – Use Combination of Natural and Hybrid

Ventilation Automatically

CO2 Demand Controlled Ventilation, Air-side Economizers (Varies with

Climate Zones)

Enhanced Particle and Microbial Filtration Technology to Lower OA

Intake Quantify

OA Intake Shut down – Chemical and Multi-gas Sensing to Close OA

Damper when Chemical Concentrations in OA Above Allowable Limits

Decoupled Ventilation (DOAS), Improved Dehumidification for Latent

Removal

AHU Discharge Temperature - Dynamic Reset of VAV System

ASHRAE Developing Cost Effective Solutions

Toward Low Energy Healthcare Buildings

Sample View of US Hospitals 1

Sample View of US Hospitals 2

Rooftop Chillers

Direct versus Indirect Lighting

Exterior Lighting

Public Waiting Areas with Window Glazing

Sample of Energy Saving Approaches

Solar Panels on Roof

Logic Controlled Sun Shade

Use Exterior Lighting

Sample of Energy Saving Approaches