The Applications of Multi-zone VAV Box Terminal Control System for IAQ Improvements May 2001 by Chuck Chin, P.Eng. Manager, Mechanical Engineering Architectural & Engineering Services, PWGSC Ontario Region and Winston Hetherington, B.B.A Building Automation System Specialist Architectural & Engineering Services, PWGSC, National Capital Area

Toronto Dominion Public Building, One Front Street

HVAC Service Calls Received by National Services Call Centre in year 00/01 GOCB’s Building Size # of Tenants # of HVAC # of HVAC Calls in Toronto m2 Tenants per 100 m2 Calls per 100 Tenants 25 St Clair Ave 31, Town Centre 33,113 1, Yonge St 52,783 1, Average w/ Std. VAV Terminal Control One Front Street 33,412 1, Reduction of Service Calls w/ Enhanced Ventilation Terminal Control ( 20.46)

Corner of a typical Town Hall

Intelligent Building Cabling System (Structured Cabling System) A typical corridor (“Street”)

A typical high density workstation (area 4.8 m2)

Personal Air Jet Diffuser Personal Intelligent Thermostat

Building HVAC Control Network with Enhanced Ventilation Terminal Control System

Enhanced Ventilation Terminal Control System with Multi-zone VAV Box Terminal Controls Network & Microcomputer Based HVAC Controls Multi-zone VAV Box Terminal Controls Individual Airflow Controls (Personal Air Conditioning)

Enhanced Ventilation with Advanced Control Technology Multi-zone VAV Box Terminal Controls

Single Zone VAV box Multi-Zone VAV box

Building Design with Advanced HVAC Technologies Individual Airflow Controls (Personal Air Conditioning)

Personal Air Jet Diffuser Personal Intelligent Thermostat

Personal Air Jet Diffuser, Personal Directional Diffuser & Personal Thermostat

Existing Conventional VAV Box Terminal System Existing base building HVAC system was installed in the late 1970s A dedicated VAV box for one HVAC zone Designed to satisfy 80% occupants (ASHRAE Standard 55), or 20% not satisfied One HVAC zone was intended for an open space, not for closed offices Temperature control: 1998 survey indicated 47% were not satisfied Air circulation: 1998 survey indicated 37% were not satisfied

Existing Conventional VAV Box Terminal System Option ‘a’: Status quote option (relocating thermostats or diffusers) This is a quick and dirty solution. It would fail to meet the PWGSC Design Standards for Acceptable HVAC Zoning and CSA Standards Z IAQ. However, it may satisfy the minimum requirement of Canada Labour Code. This option is not acceptable if IAQ is a concern.. 2

PWGSC Design Standards for Acceptable HVAC Zoning Each corner office one zone and each private office one zone Maximum of 50 m2 for a perimeter area one zone Maximum of 100 m2 for an interior area one zone The above requirements are intended to improve temperature controls. PWGSC “An Architect’s Guide for Sustainable Design of Office Buildings” (1999). “Designing small thermal zones” “Have a greater number of HVAC zones with more flexible systems and capable of being reorganized to cover small areas”

CSA Standard Z Guideline for Managing IAQ in Office Building Air Circulation Requirements The HVAC system should……provide effective air distribution to each workstation……at the minimum supply air circulation of 4 L/s per m [b] Supply air should be……that air velocities in the workstations, at desk level, are within a range of 0.05 and 0.15 m/s. This is especially critical for supply-air diffusers in VAV systems Open-Office Privacy Screens [b] screens should not create areas smaller than 10 m2. [c] the maximum height of screens should not exceed 1.5 m. [d] where air-circulation requirements cannot be met, use of supply-air diffusers or desk-mounted supply fans operable by the occupant should be considered.

HVAC Options Option ‘a’ - 74 Existing HVAC zones Status Quote Option ‘b’ HVAC zones Standard VAV Box Terminal Controls Option ‘c’ HVAC zones Enhanced Ventilation Control System (with multi-zone VAV box terminal controls)

Conventional VAV Box Terminal System Option ‘b’: Standard DDC VAV box system (186 zones instead of existing 74 zones) This solution would meet the PWGSC Design Standards for Acceptable HVAC Zoning but not CSA Standard Z for IAQ. Also, it is a very inflexible for future layout changes

Multi-zone VAV Box Terminal Control System This is the most flexible system to match the HVAC zoning requirements. This system allows the existing HVAC zones to be reorganized without the need of major ductwork modifications

Multi-zone VAV Box Terminal System with Individual Airflow Controls Option ‘c’: 74 Multi-zone VAV boxes (600 zones) with individual airflow controls. This solution would meet PWGSC zoning requirements and CSA Standard Z for IAQ. Also, this is the most flexible system to match any future floor layout changes.

Option b: Standard DDC VAV Box Sys Option c: Multi-zone VAV box Control System

Summary of Mechanical Options North York Government Of Canada Building Co-location Project

Long Tern Benefits with Enhanced Ventilation Controls

Enhanced Ventilation Terminal Control System with Multi-zone VAV Box Terminal Controls Network & Microcomputer Based HVAC Controls Multi-zone VAV Box Terminal Controls Individual Airflow Controls (Personal Air Conditioning)

Conclusions HVAC is the number one source of IAQ problems. Temperature controls and air circulation are the major areas of complaints (BOMA Study 1989 and PWGSC Survey 1998) A standard VAV box system may conform to Canada Labour Code, but is not recommended if IAQ is a concern. The status quote option is not an acceptable solution to IAQ problems For a HVAC upgrade project, the consultant should be instructed to consider all available options that can meet PWGSC Design Standards and CSA Z204 IAQ Guideline. A life cycle cost comparison should be performed to determine the most cost effective HVAC upgrade option Enhanced Ventilation System including network & microcomputer based HVAC controls, multi-zone VAV box, and individual airflow controls can be the most cost effective solution to an IAQ problem. Also, these advanced HVAC technologies can be used as effective green building design strategies

List of available Personal Air Conditioning Systems Enhanced Ventilation Control System Johnson Controls “Personal Environmental Module” Individual Airflow Control with Underfloor Air System Individual Airflow Control with Integrated Furniture System “Zero Complaint System” and Reference Materials

Building HVAC Control Network with Enhanced Ventilation Terminal Control System

Johnson Controls “Personal Environmental Module” 430 units installed in an office building at West Bend Wisconsin in 1991 An independent study indicated the impact on productivity was 2.8 to 12.8%

Individual Air Outlet with Raised Floor

Individual Air Outlet with Integrated Furniture System

“Zero Complaint System” or “McGill Jet”

Table 1 - HVAC Service Calls Received by National Services Call Centre in year 00/01 GOCB’s Building Size # of Tenants # of HVAC # of HVAC Calls in Toronto m2 Tenants per 100 m2 Calls per 100 Tenants 25 St Clair Ave 31, Town Centre 33,113 1, Yonge St 52,783 1, Average w/ Std. VAV Terminal System One Front Street 33,412 1, Reduction of Service Calls w/ Multi-zone VAV Terminal System ( 20.46)

Table 2 - Summary of Mechanical Options North York Government Of Canada Building Co-location Project

Figure 1 - Standard (Single zone) VAV Terminal System vs. Multi-zone VAV Terminal System

Fig. 2 -Future Building HVAC Control Network (with Enhanced Ventilation Terminal Control System)

Fig. 2 -Future Building HVAC Control Network (with Enhanced Ventilation Terminal Control System ) Figure 1 - Single zone VAV box vs. Multi-zone VAV box Table 1 - HVAC Service Calls Received by National Services Call Centre in year 00/01 GOCB’s Building Size # of Tenants # of HVAC # of HVAC Calls in Toronto m2 Tenants per 100 m2 Calls per 100 Tenants 25 St Clair Ave 31, Town Centre 33,113 1, Yonge St 52,783 1, Average w/ Std. VAV Terminal Control One Front Street 33,412 1, Reduction of Service Calls w/ Enhanced Ventilation Terminal Control ( ) Table 2 - Summary of Mechanical Options North York Government Of Canada Building Co-location Project