ASHRAE Journal - March 2009 - (Page 24)

Photo 1: RC-1 outdoor condenser ἀrst phase heat injection. Photo 2: FAU-1 with view of RC-1 integrated. 1 to Dec. 31, 2006. The electrical consumption and cost was 6,207,600 kWh, $385,634 (Canadian), respectively. The building’s lighting system consisted of mostly old T12 fluorescent lamps which are considerably less efficient than the fluorescent fixtures that are currently available on the market. During the 12 months of 2006, on average, 89.7% of the building’s rentable space was occupied. An energy management system was proposed to the building managers, which would control peak electrical demand (by load shedding) so that they could increase the occupancy rate without worrying about excessive demand penalties. During the energy audit carried out by the authors’ firm, we proposed to reduce the total annual energy consumption by 32% and to manage the peak electrical demand. Natural gas consumption was to be reduced by 52% and electrical consumption by 21%. Furthermore, our goals included reducing the equivalent annual CO2 emissions of the building by 500 tons (454 Mg). We wanted the costs for these measures to have a simple two-year payback, and we did not want to compromise the existing air quality. How was it done? Solving the Problems Photo 3: RC-1A outdoor evaporator ἀrst phase heat recovery. The energy-saving measures are in three categories: automated direct digital controls, HVAC systems, and electrical measures. Careful attention was given to maintaining existing air quality. The energy-saving measures that concern the automated DDC are: reducing the air conditioning during winter, and readjusting winter setpoints to minimize energy use. These measures were achieved by installing and programming a full set of direct digital controls. Each floor has peripheral zones heated by fin-tubes and interior zones cooled with AC units. The air conditioning is reduced by decreasing the setpoint in FAU-1 for the fresh air. It was originally hardwired to 68°F (20°C) and delivered to the central building core, but after the controls were installed it was made variable, allowing for effective free cooling delivered directly to the AC units with VAV control. The winter setpoints of the interior zones were readjusted to 74°F (23°C), and those of the peripheral zones were readjusted 24 ASHRAE Journal to 71°F (21°C), so heat can migrate naturally from the cooled zones to the heated zones (Figure 1). Three HVAC measures were implemented. The first consists of installing two 3,000 MBh condensing natural gas boilers to replace the existing four 4,000 MBh atmospheric boilers. Hot water from the boilers is supplied to the fin tubes in the peripheral zones, but by controlling its temperature the DDC maintain the return water temperature low enough for condensation to occur in the new boilers. The second measure consists of installing a heat recovery unit that will transfer heat from the building’s exhaust air to its fresh air. It uses an innovative heat recovery apparatus that is discussed in the innovation section. The third measure consists of diverting the water for the condensers of the AC units into heat exchangers in the fresh air supply. The water was diverted from the winter cooling tower, reducing the operation of the cooling tower. Heat that would otherwise be rejected to the atmosphere is transferred to the building’s fresh air. The second and third mechanical measures are illustrated in Figure 1. ashrae.org March 2009 http://www.ashrae.org

Table of Contents Feed for the Digital Edition of ASHRAE Journal - March 2009

Contents Commentary Industry News Letters Meetings and Shows Special Section 2009 ASHRAE Technology Awards Feature Articles Heat Recovery for Office Tower Air Motion Control in the Hospital Operating Room Anniversary Feature: Five Defrost Methods for Commercial Refrigeration Groundwater Issues: Commercial Open Loop Heat Pump Systems Used Filters and Indoor Air Quality Building Sciences Emerging Technologies Washington Report Products Special Products People Classified Advertising Advertising Index

ASHRAE Journal - March 2009

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