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Unformatted text preview: quoted price to
install the system was ∼$150,000. The contractor
also provided an estimate of the annual energy cost
to cool the fresh-air of ∼ $4,400.
• The motion to proceed with the quote did not pass.
• The residents have asked UW Engineering to
suggest alternative solutions. In particular, the
residents have expressed interest in “energy
efficient” options. contractor proposed new cooling system Roof-Mounted
Condenser Unit Cool Elec Heat Refrigerant Lines Air
Duct Fresh-Air Unit Roof Corridor
/ Residential Suite exfiltration/exhaust
(to outdoors) 15th Floor Corridor
/c Residential Suite exfiltration/exhaust
(to outdoors) 14th Floor Corridor
13th Floor To other floors Residential Suite exfiltration/exhaust
(to outdoors) Bauer Lofts -- 12th Floor Layout 12th Floor Layout – “Common Areas” Indicated 12th Floor Layout Residential
Suite 12th Floor Layout – Common Areas stairs
trash corridor air duct air duct Elec Heat Heat 5500 cfm Air
Intake Elec 7000 cfm Fresh-Air Unit Air
Fresh-Air Unit Roof •
• heating sections
fan motors are
both 5 hp 15th Floor 5500 cfm
+ 7000 cfm
12,500 cfm 14th Floor 13th Floor To other
(8760 hrs/year) Additional Info
• In-Suite Heating and Cooling is provided by a waterloop heat-pump system.
– Each suite has a heat-pump connected to a
shared water-loop. (Some larger suites have more
than one heat pump.)
• If a suite needs heat, the heat-pump absorbs heat from the
loop and delivers it to the suite.
• If a suite need cooling, the heat-pump absorbs heat from the
suite and rejects it to the loop.
• If the water-loop temperature drops, natural-gas fired boilers
provide heat addition.
• If the water-loop temperature rises, a fluid-cooling (i.e.
cooling-tower) provides heat rejection. Simplified Schematic Representation of a
Water-Loop Heat Pump System
tower return pipe supply pipe boiler ZONE 1 ZONE 2
T Zones terminal units:
water-to-air heat pumps Note: Bauer Lofts has approximately 250 heat-pumps. T Partial Schematic Diagram of the Water-Loop Heat Pump System Partial Info on the Contractor Proposal: Estimate of Annual Cooling Electricity Provided by Contractor: Example Refrigerant and Air Temperatures for a “DX Air Conditioner”
Tair,outdoor = 35°C Outdoor
Air Tcond = 52°C
valve Tevap = 4°C
Air Tair,in = 24°C compressor Tair,out = 13°C
Evaporator Coil Schematic Depiction of “Water-to-Air” Heat Pump
Reversible vapor compression refrigeration cycle COMPRESSOR REVERSING
VALVE fan +
HEAT EXCHANGER REFRIGERANT-TO-AIR
HEAT EXCHANGER Building Energy Performance – Spring 2012 - Topic 21 Aspects of Building Energy Codes
& Green Building Rating Systems Building Codes
• Building Codes are typically used to define a minimum
acceptable level of “good practice” for certain aspects of
building design and construction. They are typically focused on
objectives such as:
Fire & Structural Protection • To a certain degree, a building code may be thought of a
describing “the worst you can legally get away with.” Building Energy Codes
• It is becoming more common in North America that building
codes (e.g. the Ontario Building Code) include provisions that
cover aspects affecting building energy performance.
• These typically describe requirements considered to be
minimum “good practice” for aspects that have an important
impact on its energy use, such as:
– Thermal resistance of walls and roofs
– Maximum window-to-wall ratio
– Minimum rated efficiencies of HVAC equipment
– Maximum allowable lighting power density Some building energy codes/standards commonly used in Canada:
• ASHRAE Standard 90.1 – Energy Standard for Buildings except
Low-Rise Residential Buildings, (“ASHRAE 90.1)”
– Under “continuous maintenance”, a new version released approximately
every 3 years
– Past releases include: 1999, 2001, 2004, 2007, 2010
– Widely used across North America • Model National Energy Code of Canada for Buildings 1997
• National Energy Code of Canada for Buildings 2011 (“NECB”) Note:
ASHRAE 90.1, MNECB, and NECB are codes/standards
that are intended to be applied to “Buildings” rather
than to “Houses” (i.e. low-rise residential).
There are other codes/standards intended for
application to houses. Overview of ASHRAE 90.1 and MNECB
Both ASHRAE 90.1 and MNECB contain sections that list
• Building Envelope
• Heating, Ventilation, & Air-Conditioning Systems
• Service Water Heating Systems
• Electrical Power Both codes list requirem...
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- Spring '12