Telus Corporate Offices
Image 1: Telus Corporate Offices
2: Facade Ventilation Operable
Window with Fritted Glass
Air Distribution System Characteristics
eight-story 11,800 m2 (127,000 ft2)
Occupancy started in fall of 2000.
A retrofitted telecommunications utility local services center and
utility executive offices.
& Associates Vancouver
Building Design Features
project involves a major retrofit of corporate offices for the British Columbia
telecommunications utility. The
building is a multistory concrete structure that is being retrofitted to be
highly energy efficient. This
project contains a number of unique features. Seven floors with 930 m2 (10,000 ft2) floor plates
have been retrofitted with UFAD systems. Each
floor is served by its own air handling system. Concrete
exterior walls retain refurbished existing single glazed wood frame double hung
windows. What may be the first
example of large scale ventilated facade technology has been installed on the
face of the building as shown in Figure 1. The double-glazed facade uses fritted glass to reduce the higher angle
solar gain (the light stripes shown in Figure 1). Occupants look horizontally through clear glass but when they look up
they see the fritted glass. Windows in
the facade are operated by the occupants via switches in the room.
Facility personnel can override these controls as well as the dampers
and fans in the cavity. The
dampers at top and bottom as, well as exhaust fans at the top, are powered by a
photovoltaic array. The dampers
and fans are controlled by a series of temperature sensors located at several
places in the cavity. The dampers
and fans are operated to allow ventilation in the summer and insulation (all
openings closed) in the winter. These
features are anticipated to reduce both heating and cooling loads dramatically,
but still allow occupants to control ventilation to their space.
inside layout is open plan although the interior of each floor has several
enclosed meeting rooms. Each floor
has multiple separate office spaces accessible via a central hallway. Floor access and service areas are located in the interior. Modular furniture from a variety of manufacturers with movable
partitions is used throughout. The
raised floor panels mounted on a stringer-less post system provides for a 0.45 m
(18 in.) plenum; floor panels are covered with glued down non-coincident carpet
tiles, 0.61 m x 0.61 m (24 in. x 24 in.).Ceilings are open, white painted exposed concrete 4.5 m (15 ft) high
with suspended direct/indirect fluorescent lighting fixtures and exposed sprinkler lines. Workstation
telecommunications and electrical wiring are provided by an access module
mounted in the floor panel, which is in turn connected to a junction box in the
plenum with 3.7 m (12 ft) whips.
Air Distribution System Characteristics
retrofit project was inspired by Telus team members who believed in green and
sustainable design and that the leading edge nature of telecom business should
be reflected in the work environment. Since
Telus is a telecommunications utility, flexibility in reconfiguring spaces and
accommodating telecommunications services was highly desirable. An UFAD system
was conceived as an integral part of a high quality indoor environment and an
energy efficient solution to space conditioning.
m (18 in.)
swirl diffusers are used for all interior and perimeter areas.
m (24 in.) wood-core panels using a stringer-less post mounting system
were supplied by APS Access Floors.
17°C (63°F), varies with load
air volume – variable temperature (CAV-VT) for delivery to the space;
variable air volume (VAV) at air handler (see below).
system depicted in Figure 3 has a number of unique design features. Each floor
uses a dedicated air handing unit (AHU) that supplies conditioned air directly
to the underfloor plenum with very limited distribution ductwork. The AHU is
fitted with a variable speed drive to maintain constant pressure for interior
zones. The perimeter system uses a
series of fan coil units (FCU), each of which is fitted with a mixing damper
arrangement that allows the unit to supply variable temperature air to the
perimeter swirl diffusers. These
units are connected to space return air ducts that draw warm air from the
ceiling area as needed. A hot
water heating coil augments the re-circulated air to provide heating. The hot water for these coils is furnished by waste heat from a nearby
process waste heat stream, virtually eliminating the use of fossil fuel for
operation of this system is divided into two main elements. In the perimeter, zone temperature sensors control the fan coil mixing
boxes by first modulating the mixing dampers and then the reheat coil control
valve when the dampers are in full re-circulation mode.
This results in CAV operation of the perimeter system as a standalone
system. The interior system floor
diffusers are operated as a CAV-VT system by varying the supply air temperature
of the AHU in response to demand from interior zone temperature sensors. Due to the fact that the perimeter system has a variable
demand on the plenum air supply depending on its mixing state, the central AHU
is operated as a VAV system to maintain constant pressure in the underfloor
UFAD System Performance
this building was reviewed during its construction before occupancy, feedback
from the designers and the owner’s representative confirms that there is a
high degree of satisfaction with the UFAD system. Occupant
control of local comfort conditions via adjustable floor diffusers and operable
windows have been cited as key factors in user satisfaction; “it just has a
nice feel to it.” The use of
fossil energy for heating has been eliminated due to use of process waste heat
for perimeter reheat coils.
comments reflect the views of CBE researchers based on a limited study of the
building and do not necessarily represent those of the designers and/or
for the groups occupying this building will be high; estimated at 50-75%.
concrete ceilings have resulted in a “harsh” acoustic environment; steps
are being taken to improve the acoustic performance.
initial occupancy and commissioning there were imbalances in the air
distribution and a noticeable difference between the interior and perimeter
air flow rates. The balance
issues have been resolved and the occupants have also learned that moving or
adding floor diffusers in their local area can address their air flow and
system is a unique and interesting solution in that it maximizes the
opportunities to save energy while maintaining good performance on the
airside. Although the perimeter
system uses fan energy from relatively inefficient small motors, it minimizes
reheat due to the mixing system and by drawing air from the ceiling area. In addition, VAV operation of the central AHU will tend to reduce fan
power requirements to some extent.
Using constant volume solutions for the perimeter and core areas ensures
operation of the floor diffusers at their optimum design point.
The perimeter mixing system combined with the process waste heat hot water
supply, and the load reduction afforded by the glass facade should result in extremely low or no fossil fuel use for heating.
Cooling energy use should likewise be reduced due to operation of the ventilated façade in summer. However, the use of the operable windows may cause problems with air and pressure balances for the
Since distribution ductwork has been eliminated, the designer anticipates using relative high static pressure 25-37 Pa (0.10-0.15 in. w.c.)
to provide air distribution. However,
this may result in excessive leakage unless care is taken to seal floor
panels and interfaces between floor and other building components.
of supply air ductwork in the plenum reduces system first cost. However, the return air duct chases that allow air to be drawn
from the ceiling area into the perimeter FCUs add to cost. Overall we would expect this system to be on par with other
similar solutions with regard to first costs.
Reviewed: February 2000 – April 2001