ASHRAE Journal - October 2011 - 51

technology award case studies
the diverted irrigation water is piped to a reinjection well, where it is returned to the aquifer (Figure 1).
Air System

the radiant heating system is used to melt snow on the sidewalks and approaches to the building.
Energy Efficiency

Building at a Glance
Name: Emergency Services Training Center Location: College of the Siskiyous, Weed, Calif. Owner: Siskiyous Joint Community College District Principal Use: Classrooms Includes: Faculty of ces Employees/Occupants: 220 Gross Square Footage: 9,885 Conditioned Space: 8,073 Substantial Completion/Occupancy: 2009 Occupancy: 100%

The air system consists of a central station variable air volume (VAV) air handler, delivering constant 63°F (17.2°C) air to displacement diffusers located throughout the building. Zone control is maintained by pressure-independent VAV boxes. Fan speed is maintained by variable frequency drives responding directly to VAV damper position. Displacement ventilation is efﬁcient and results in high indoor air quality. Air is delivered to the space at a higher temperature than conventional mixing systems, thereby requiring less cooling. This is because the air only needs cooling to 63°F (17°C) rather than 55°F (13°C), thereby requiring less cooling capacity. It displaces warm air and contaminants, increasing indoor air quality in the occupied zone. Additionally, the high portion of outdoor air (88%) and the use of active ﬁeldpolarized ﬁltration increase the indoor air quality signiﬁcantly over a standard code-compliant air system. The ﬁlters are rated at ASHRAE MERV 11, with a low average pressure drop of approximately 0.375 in. w.c. (93.3 Pa). Temperature controls are provided by state-of-the-art direct digital controls system, which is connected via the internet to the campus-wide infrastructure.
Heating System

The building’s thermal performance and annual energy use were simulated using a commercially available computer modeling program. The program is certiﬁed by the California Energy Commission for use in showing compliance with California Title 24 Energy Standards. The software uses the DOE-2 engine. Results show that the building’s overall proposed annual energy use exceeds the requirements of California Title 24 and ASHRAE/IESNA Standard 90.1-2007 by 34%. The cooling and heating systems simulation show that both systems substantially exceed minimum standards. The cooling system energy use is estimated to be 0.07 kBtu/ft2·yr (794 957 kJ/(m2·yr) and the heating system energy use is estimated to be 2.0 kBtu/ft2·yr (22 713 053 kJ/(m2· yr). The cooling system uses less than 1% of the energy allowed by the standard design and the radiant heating system uses a little more than 10% of the energy allowed by the standard design. The energy efﬁciency ratio (EER) Btu/h·W input for the cooling system is approximately 94. When fan energy is included, the overall EER is 21.6.
Indoor Air Quality

ASHRAE winter design temperature for Weed is 4°F (–15.6°C). The heating system is radiant. Hot water is piped from a condensing boiler (92% thermal efﬁciency) to a pre-heat coil in the air handler and to several zone water manifolds. Hot water heats the ﬂoor slab through serpentine cross-linked HDPE piping. Hot water supply temperature never exceeds 120°F (48.9°C), and return water is designed for 90°F (32.2°C) or lower to ensure maximum boiler efﬁciency. Additionally,
October 2011

Minimum ventilation requirements per ASHRAE Standard 62.1, ASHRAE Standard 55, and the California Building Code were calculated to be 2,400 cfm (4,078 m3/h). With VAV systems, it is difﬁcult to determine if a particular zone is getting the minimum code ventilation rate, even if ventilation air is being measured at the air handler. This difﬁculty is eliminated when using high outdoor air fraction and the minimum position of all VAV boxes exceeds the minimum ventilation rate. At minimum airﬂow (all VAV boxes at 40%

capacity), the ventilation rate (with 88% minimum outdoor air quantity) is: 8,000 cfm × 0.40 × 0.88 = 2,816 cfm, which exceeds the calculated minimum rate of 2,400 cfm (4,078 m3/h). Using displacement ventilation systems all but eliminates drafts, and “displaces” warm air and contaminants up and away from occupants, where it is then exhausted from the building. Using MERV 11 air ﬁltration exceeds minimum requirements. The air handler is equipped with active ﬁeld-polarized ﬁlters, attaining MERV 11 without the typical high pressure drop associated with bag or rigid ﬁlters.
Innovation

The cooling system uses water whose infrastructure exists for an entirely different purpose (irrigation). Using displacement ventilation with its relatively high delivery temperature makes it possible to fully cool the building without supplemental mechanical cooling. The low ambient moisture content and large
ASHRAE Journal 51

ASHRAE Journal - October 2011

Table of Contents for the Digital Edition of ASHRAE Journal - October 2011