Wayne Aspinall Federal Building

The existing building enclosure consists of thermally massive masonry construction. This inherently results in stable temperature within the building. To reduce heat transfer, roof surfaces were upgraded to R-35 average with rigid insulation, wall surfaces were insulated with 2" of polyiso spray foam insulation, and new storm windows were installed inboard of existing historic windows. Storm windows are treated with a 3M solar control film. WUFI, THERM, and thermographic imaging analysis were performed during the design phase.

3M Prestige Series Solar Film

Prestige Series by 3M

The 3M Prestige Series Solar Film allows for control of solar gain in retrofit applications, without compromising daylighting potential. Care should be applied when selecting the film to use, including the following factors: heat strength of glass, desired reflectivity, and exposure of film to handling.

All major lighting systems were upgraded in the building, using a combination of fluorescent and LED sources. Historic lighting fixtures from the original design era of the building were replicated. The average lighting power density is 0.75 W/sf.

Building information modeling was used throughout the design and construction process to ensure coordination of all services within an existing historic structure. The HVAC approach was designed to respect the historic fabric of the building. The use of a dedicated outdoor air system (DOAS) allowed ductwork to be significant reduced in size. System components include a DOAS with evaporative cooling and fixed plate energy recovery heat exchanger, 32 well (450 ft deep) GeoExchange loop, and a water-source variable refrigrant flow (VRF) system. Carbon dioxide sensors are provided in all densely occupied spaces to control shut-off VAV boxes. To allow for energy balance of the GeoExchange loop, a closed circuit evaporative fluid cooler is installed on the roof.

Mitsubishi VRF System

WR2 by Mitsubishi

Variable refrigerant flow (VRF) systems (also known as VRV) have been successfully used for over 25 years, first in Asia, then in Europe. VRF systems allow multiple indoor fan coil units to be served from a single condensing unit, with some systems capable of simultaneous cooling and heating. Systems are known for high efficiency and application flexibility. Indoor fan coil units use Sirrocco type fans, which have a low acoustic footprint. Designers must use care to provide sufficient access to fan coil units for filter change and also consider ASHRAE 15 refrigeration safety requirements. The Mitsubishi system uses a two-pipe refrigerant piping network; other manufacturers use a three-pipe system. WRL will provide commentary on two-pipe versus three-pipe systems as a separate blog post. Units are available in water-source or air-source configurations. Application note (March 2013): designers should use care when specifying twinned water-source VRF units in a variable condenser water flow application. Units are not able to natively modulate an associated control valve. Previously published application guides incorrectly indicated this as a design feature. For designers looking for variable flow applications, consider units by LG or Daikin, which are available with a specialized control module.

Recold Evaporative Fluid Cooler

JW Series by Recold

Evaporative fluid coolers utilize the same evaporative cooling principles as a traditional open loop cooling tower, except the process fluid is not exposed to ambient conditions. Fluid is directed through a copper heat exchanger. This provides the benefit of reduced water treatment and also protects HVAC equipment from fouling. Applications include heat rejection from data center systems as well as load balancing of GeoExchange systems.

Due to the use of photo-voltaic panels to generate the building's required energy, the use of an electric based service hot water heating system was preferred. Point-of-use electric water heaters are provided for all lavatory faucets, allowing for elimination of losses from a traditional system with a recirculation loop. During the design phase, solar thermal system were also evaluated, but it was determined that utilization of a system for a site net zero energy building would be challenging: a system sized 100% heating during the winter would produce excess and unusable capacity during the summer.

Plumbing fixtures are EPA Watersense labeled: 0.125 gpf urinals and 1.28 gpf toilets.

EEMax Instantaneous Water Heater

by EEMax

Commercial service hot water heating design requires care, to ensure delivery of hot water to the most remote fixture within a reasonable period, to reduce the waste of water. Commercial buildings will usually incorporate a recirculation water loop, to keep primary plumbing piping filled with heated water. Recirculation energy losses, due to pump energy, as well as heat transfer, can be substantial. An alternative is to use point-of-use heaters. Electric tankless units are compact and can be installed underneath each plumbing device that requires hot water. Temperature regulation is good. Designers should utilize care to understand a building's potable water quality and to coordinate electrical requirements early. Buildings which derive electrical energy from utility companies reliant on coal based plants should analyze the overall impact of point of use heaters on greenhouse gas emissions, versus natural gas systems.

Sloan Pint Flush Urinal

ECOS 8186 by Sloan

While energy use reductions have traditionally gained the most attention in commercial building design, designers are now also focusing their attention on water use reduction. Water stress continues to increase in more parts of the world and is expected to be the next major resource of concern impacting the United States. Buildings that used the first generation of waterless urinals saw mixed results, due to the requirement for special traps needing regular replacement. Waterless urinals retrofitted into existing buildings were often problematic when existing piping was not properly pitched for proper fluid discharge. The pint (0.125 gallon per flush) urinal provides significant water savings, while addressing some of the challenges with waterless urinals. Pint urinals are now a WRL minimum standard.

The building is served by a 123 kW photo-voltaic array. Approximately 70% of generation capacity is located on an elevated canopy, with the balance located at roof level. The SunPower E20 series was selected for its efficiency, which was necessary to provide sufficient production on the building itself (NREL Class A). During the design process, the Sanyo HITT Double series was also evaluated. The design team decided to eliminate row to row spacing between panels, to eliminate the potential for shading from panel to panel.

Renewable energy systems are design to not be visible from street level along the main South elevation, to comply with guidance by the Secretary of Interior's Standards for Historic Preservation.

SunPower E20 PV Panel

E20 by SunPower

The photovoltaic panel market is saturated with a variety of manufacturers. SunPower currently manufactures the most efficient panel available on the market, with average panel conversion efficiency of 20%. Selecting an appropriate panel is not straightforward, as cost, warranties, temperature performance, weight, and manufacturing capability all need to be considered. WRL will be developing a white paper on panel selection in early 2013, with annual updates on the product market.

Process loads, such as computers and appliances, represent a significant portion of energy consumption for a low-energy building. While these components are not currently regulated by energy code, they require consideration by building occupants. WRL has worked with GSA on education of tenants to reduce personal energy use. Portable heaters, individual refrigerators, and incandescent task lighting are all banned from the facility. Tenants are encouraged to use laptop computers, rather than desktop computers, due to a 75% reduction in energy footprint. Each workspace has controlled receptacles, whereby equipment will automatically be shut off based on the output from occupancy sensors.

The building relies on a significant amount of metering and control technology. Wireless devices based on the EnOncean Alliance protocol do not require batteries and reduce wiring requirements through the historic building significantly. The buidling systems have been designed to meet the goals of the GSA's Smart Buildings initiative, which includes use of a converged network: multiple building systems share a common network backbone where possible. We discovered there are still some barriers to consolidating IT systems in a multi-tenant building.

EnOcean Alliance Wireless Protocol

by EnOcean Alliance

Wireless technology is pervasive in our lives. From a single wireless access point, dozens of devices can be controlled, without the need for hard-wired cabling. Devices can be relocated and reprogrammed using software-based solutions. The EnOncean Alliance is a consortium of companies focused on self-powered interoperable wireless building control systems. The Alliance has developed a wireless standard, as well as devices which rely on small changes in motion, pressure, light, temperature, or vibration for energy. Batteries are typically not required. The ZigBee Alliance has developed the major competing wireless standard.