Discovery Elementary

Images

Discovery Elementary
architect speaking to schoolchildren about green building
In this photo, architect Wyck Knox speaks to children at Discovery Elementary School about their new zero energy building.
Credit: Photo copyright Lincoln Barbour
Discovery Elementary Exterior
photo of elementary school with children playing on lawn
Children in the photo play on the lawn outside Discovery Elementary, a zero energy school.
Credit: Photo copyright Lincoln Barbour
Discovery Elementary Cafeteria
children eating lunch in a daylit cafeteria
Through the use of glazing protected by ample shading, children seen in this photo can enjoy ample daylight in the cafeteria during their lunch hour.
Credit: Photo copyright Lincoln Barbour

General Information

Quick Facts

Location

Arlington, VA

Project Information

Project Owner

Arlington County, Virginia

Occupant Type

Local government

Currently experiencing a population boom, Arlington County is facing massive growth in the next decade and is seeking to add half a million square feet in educational facilities. During competitive design procurement for Discovery, one of the teams suggested a zero energy goal could be accomplished within the given budget. Proponents at the district level who had been championing energy efficiency were receptive, but were skeptical that it could be done within the budget aimed at LEED Silver. Not only did the project end up coming under budget including the solar array, the building is more efficient than the originally predicted. Now Discovery saves $100,000 per year in utility costs, enough to cover the salaries of two teachers.

Location Details

Address

5241 N. 36th St., Arlington, VA

Site context/setting

Suburban

Occupancy

Typical Number of Permanent Occupants

715

Owner Occupied

Yes

Building Details

Scope

GENERAL FLOOR AREA

Total Gross Floor Area 98,000 ft²

BUILDING

Building unit or complex: Described project is a single building
Percent New 100%

COMPLETION

DATE OF OCCUPANCY/COMPLETION

August 2016

Architectural Details

SUSTAINABLE MATERIALS AND RESOURCES USED IN THE CONSTRUCTION AND LANDSCAPING

ARCHITECTURAL MEASURE USED TO MEET A HIGH-LEVEL OF ENERGY PERFORMANCE

Discovery was built adjacent to an existing middle school on a portion of the site that was previously considered unusable because of a sloped hillside. Even with those constraints, the design team experimented with various shapes and orientations for the new 630-student school. Every version was analyzed for energy efficiency and described in terms of how many solar panels it would take to offset the energy load. The model that performed best was actually rejected. It was too compact and did not have enough sun exposure for daylighting.

Process

Design Process

Architecture firm VMDO suggested zero energy during competitive bids, claiming it could be done within the existing budget. The school board was interested in the concept but assumed that purchasing the solar panels would be too expensive. They decided to go forward with the project and design for a zero energy-ready building and then bid the renewable energy systems as an alternate. When the bids came in, however, the zero energy version was still $1 million less than the original budget.

During design, an engineering firm that had successfully designed several zero energy schools in Kentucky was brought onto the team. The firm had experience with designing and modeling exterior wall assemblies constructed with insulated concrete forms—a construction technique that is rarely used in Virginia but that offers high R-value, high thermal mass, and good air sealing. Add LED lighting and geothermal wells for a ground-source heat pump system, and they had the main ingredients for a highly efficient school.

Design Tools

Lessons Learned

Discuss goals that were met and goals that were not achieved, and the reasons for these outcomes

For the project team, the lessons learned from Discovery have been about tracking performance and understanding maintainability. Most sustainability programs are based on predicted energy use, but zero energy requires proven performance. And part of tracking actual performance means the design team is more in touch with problems that crop up during operations. The team learned that making things simpler to operate—rather than automating everything in a way that gets overridden when occupants complain—was one key to success.

Finances

General

How the Project was Financed

Bond

Total Project Cost

$32,305,800

Project Costs

Property Acquisition Costs

$0

Project Costs

Building only: $26,690,000 PV: $1,510,000 Sitework: $4,106,000

Details

Estimated payback time of any investment in measures needed to reach zero net energy

Simple payback on the photovoltaic system at Discovery is estimated to be 13 years. However, analyzing the financing from a whole-project perspective, the cost savings from the building being energy efficient (approximately $100,000 per year) more than make up for the bond payment on the solar array. Furthermore, the array generates income when the building is energy positive, so the system was actually cash flow positive from day one.

Incremental costs related to building envelope, lighting, HVAC, and renewable energy technologies incurred to achieve net-zero energy

PV: $1,510,000

Financing Mechanisms

Procurement process
  • Design-bid-build
Loans
  • Bond

General Energy

General

Energy Use

Typical site EUI for the district is 69. The energy model predicted an EUI of 21, but actual performance is closer to 16.

Building Envelope Thermal Performance and Mechanical Systems

Insulated concrete forms (8 in. concrete core and 2 in. polystryrene form walls)

Geothermal wells and small, distributed floor-mounted heat pumps, demand control ventilation

Energy Systems

1,700 photovoltaic panels, 496 kW

Energy Balance

Aspects of the project that were included in balance calculations

  • Heating
  • Cooling
  • Lights
  • Plug Loads
  • Other

Energy Generation Source Locations

  • Generate renewable energy within its footprint (e.g. solar PV on the roof)?

Energy Datasets

Dataset NameYearTypePurchased Energy (kBtu/ft²)
20162016Actual--end-use metering-0.65