Photo credit: Robb Williamson

Energy

Ground-source heat pumps are linked to a closed-loop, ground-source heat pump well field that provides HVAC heating and cooling supply as well as domestic hot water heating. Raised-access flooring provides an underfloor supply air plenum for displacement heating and cooling air distribution through floor-mounted air diffusers.

A 14.3 kW PV array mounted on south-facing sloped roofs provides 28% of the total energy costs. Several of these PV panels are mounted on solar tracking devices.

Heat recovery air-handling units provide ventilation make-up air separated from conditioned air, thereby allowing for conditioned air equipment to be shut off when not needed. Ventilation air is preconditioned through energy recovery, which also provides the necessary dehumidification for the system.

Fourth-generation design of light shelves on south-facing windows increases lighting levels by reflecting natural light deeper into interior spaces; at the same time, cooling loads are reduced by shading windows from exposure to summer solar radiation.

Site-specific reverse-baffle solar shading devices were designed to shade other south-facing windows from high-altitude summer sun while allowing low-altitude winter solar radiation to penetrate into interior spaces. Second floor south-facing windows are shaded via integral roof overhangs.

Lighting power density is reduced to an average of less than 0.75 W/ft2 (8 W/m2), which significantly reduces both electrical energy consumption and cooling loads. This was accomplished by integrating the following components: split task/ambient lighting scheme; indirect fluorescent lighting fixtures with T-8 lamps and electronic dimming ballasts controlled by light-level sensors; natural daylighting via clerestory window monitors; occupancy-sensored switching at workstations, toilet rooms, and conference rooms; roll-down solar shades and south-facing windows; compact fluorescent lighting fixtures with vertical lamp configurations; and LED exit signs.

Manufactured wiring distribution systems incorporate relocatable floor boxes mounted in access floor panels with quick-disconnect cabling to provide maximum flexibility for tele-data and power provisions. Such flexibility supports workstation reconfigurations and minimizes chum rate costs.

The building's thermal envelope achieves high-performance levels by integrating exterior walls constructed of highly insulating—R-30 (RSI-5.3)—EPS structural concrete wall forms; high-density fiberboard roof decking laminated with an interior reflective surface coupled with 4 in. (100 mm) of rigid polyisocyanurate insulation to provide a composite roof insulation of R-33 (RSI 5.8); pre-manufactured aluminum-clad windows which provide triple-glazed, low-e coated, argon-filled insulating glass with a whole-unit U-value of 0.29 (1.6 W/m2*C); storefront window fabrication including high-performance, thermally broken frames and triple-glazed, low-e coated, argon-filled insulating glass with a whole-unit U-value of 0.26 (1.5 W/m2*C); and a concrete floor slab on grade which is insulated with 2 in. (50 mm) of EPS rigid insulation.

This high-performance thermal envelope, in conjunction with space planning that locates no workstations directly adjacent to window walls, eliminated the need to design separate perimeter thermal zones and supplemental perimeter heating systems.

All of the above systems are integrated to achieve an annual energy consumption, as currently simulated, that exceeds the requirements of ASHRAE/IES Standard 90.1, 1989 by 30% and equates to less than 40,000 Btu/ft2 (450 MJ/m2).

Systems integration also reduced nominal cooling capacity to 52 tons (183 kW), which equates to only 658 ft2/ton (58 W/m2).

Building commissioning is specified according to the Bonneville Power Administration's Building Commissioning Guidelines. The building is equipped with permanently installed energy consumption monitoring equipment.

 

Energy Data Set: Actual & simulation hybrid: Units: English Metric

Annual Purchased Energy Use
Fuel	Quantity	Cost($)	MMBtu	kBtu/ft2	$/ft2
Electricity	406,000 kWh		1,390	38.5
Annual On-site Renewable Energy Production
Fuel	Quantity		MMBtu	kBtu/ft2
Photovoltaics	17,000 kWh		58	1.61
Total Annual Building Energy Consumption
Fuel		Cost	MMBtu	kBtu/ft2	$/ft2
Total Purchased			1,390	38.5
Total On-Site Renewable			58	1.61
Grand Total			1,440	40.1

Annual End-Use Breakdown
End Use	Quantity	MMBtu	kBtu/ft2
Heating	45,000 kWh	154	4.27
Cooling	17,900 kWh	61.1	1.7
Lighting	186,000 kWh	635	17.6
Fans/Pumps	146,000 kWh	498	13.8
Plug Loads and Equipment	103,000 kWh	351	9.76
Vertical Transport
Domestic Hot Water	40,000 MJ	37.9	1.05
Other
Unspecified End Use		-293	-8.15

Peak Power
Fuel	Quantity	English
Electricity (Summer)	90 kW	2.5 W/ft²

Building Energy Load
Load
Cooling Load	54.3 ton	663 ft²/ton
Connected Lighting	23.4 kW	0.65 W/ft²

Data Sources & Reliability

Simulation software
Breakdown by end use from DOE-2 simulation.

Utility bills
GOU Energy - February 2001 to January 2002

 

Green Strategies

• Wall Insulation
  • Achieve a whole-wall R-value greater than 25
• Ground-coupled Systems
  • Use ground-source heat pumps as a source for heating and cooling
• Daylighting for Energy Efficiency
  • Use north/south roof monitors and/or clerestories for daylighting
• Photovoltaics
  • Use a photovoltaic (PV) system to generate electricity on-site
• Lamp Ballasts
  • Use automatic-dimming electronic fluorescent lamp ballasts in conjunction with daylighting
• High-performance Windows and Doors
  • Use windows with a whole-unit U-factor less than 0.32 (greater than R-3.0)
• Ventilation Systems
  • Use displacement ventilation
• Lighting Controls
  • Use modulating photoelectric daylight sensors
• Roof Insulation
  • Achieve a whole-roof R-value of 25 or greater