Design Specifications

The Gilman Ordway Campus of the Woods Hole Research Center

Insulation

To achieve the targeted insulation levels, wall assemblies were constructed using offset stud wall construction. This eliminated direct thermal transmission to the exterior by any part of the buildings structure, and provided a sufficient wall cavity depth (8 to 10”) for the required insulation. Where this was not possible (under the mansard roof of the original structure) 1” foil-faced polyiso board was installed over the insulated rafter bays (6 ” true depth).

The insulation used is an HCFC-Free, sprayed-on polyurethane with the tradename Icynene.

Above the roof deck 4” of rigid polystyrene insulation board was installed on both the original building and the addition for an insulation value of approximately R-45 when combined with the polyurethane insulation applied to the underside of the roof. Rubber membrane roofing was installed over the insulation board.

Windows and doors

High-performance window glazing was selected for the windows and doors. In the renovated building argon-filled double-glazed windows with a low-E coating were installed (with effective R of 4.1). Exterior doors throughout the facility matched the windows of the renovated building. Where areas of glazing are greater in the new construction, triple-glazed argon-filled windows were used, with a single low-E coating, an effective R of 5.4, and solar heat gain coefficients of 0.24.

Mechanical Systems

The focus of the HVAC system design was four fold:

1. Enable use of passive heating, cooling and ventilation whenever possible
2. Employ a ground source heating and cooling system
3. Utilize low temperature heating distribution systems
4. Recover or reject energy using enthalpic energy recovery ventilation when the building is in an active mechanical mode

The resulting building is all electric. No fossil fuels are delivered to the site.

The ground source heating and cooling system is based on a standing column well. This open loop system extracts source water from the ground near the bottom of an uncased well 365m (1200’) deep and returns the water near the top of the well. Total installed heating capacity in the building is 15 tons (180Mbtu).

A total of 6 heat pump units are used. Two water-to-water heat pump units (WWHPs) are connected to a hydronic distribution loop which deliver heating and cooling to all the offices. Four water-to-air heat pumps (WAHPs) provide heating and cooling to large open spaces such as the auditorium, the commons and the laboratory. All the heat pumps employ highly efficient scroll compressors.

The WWHPs are connected to a buffer tank, to prevent short-cycling, and the buffer tank is connected via the hydronic distribution system to individual valance convectors in each of the offices. These valances are connected to a condensate drain line to remove condensate during summer cooling.

Enthalpic energy recovery ventilators (ERVs, also referred to as energy recovery units - ERUs) are used in the building to recover (or exclude) both sensible and latent heat to and from the building. Each office is supplied with ~ 20cfm of pre-conditioned fresh air from the ERV. WAHPs also are supplied with a fraction of fresh air by way of the ERVs.

Lighting

Occupancy sensing lighting controls are employed in all of the offices and throughout the building. These sensors are connected to electronically ballasted T-8 lighting fixtures or compact fluorescent (CF) lamps. CF task-lighting is provided at the desktops.

Solar photovoltaic system

A direct to grid solar photovoltaic system of 26 kWpeak (DC rated) capacity is installed. The system is mounted flush to the roof surface which itself is angled approximately 8 degrees (towards the South) from horizontal. The building faces 10 degrees west of due solar south and is not shaded by vegetation or other obstructions. A total of eighty-eight 300 watt ASE (now Schott) photovoltaic panels, totaling 196 m2 are connected in eleven series strings to eleven 2.5 kW SMA grid-connected inverters.

The system is metered with a revenue grade meter (ION 6200) whose pulse output is directed to the building energy monitoring system, which records production in 0.2 kWh increments.

The PV system is mounted horizontal to the roof plane for aesthetic reasons (from the street side perspective of the original building), and also due to issues of self-shading, which occurs at low sun angles when mounting to a low pitch roof structure.

Solar Thermal System

A modest, residentially sized solar domestic hot water system was installed. The system consists of three 4’x8’ flat plate collectors mounted at a 45º angle. Water serves as the heat exchange medium with freeze protection ensured by a drain-back configuration. A typical 35 gallon stone-lined storage tank is used with an in-tank ½” copper fined-tube heat exchanger 20’ in length. The system employs a “head tank” located in the top floor of the building within the conditioned space to minimize the head that the circulating pump must overcome to establish flow. A single ~ 60 watt circulating pump controlled by a differential temperature controller delivers heat to the storage tank in the basement. The solar thermal tank preheats water, which is delivered to a standard 120-gallon electric resistance hot water heater whose temperature is set at 110°F. A secondary hydronic circuit with a small circulator pump circulates heat from the solar tank to the top of electric water heater when the temperature of the solar tank exceeds that of the electric water. This increases the effective mass of solar storage significantly during warmer periods of the year when it is available. For the period of May through November the Solar thermal system provided 88% (1684 kWh) of the total energy required for domestic hot water.

Office Equipment

Significant efforts were made to select low-energy office equipment. Desktop computers have largely been replaced with notebook computers, flat panel displays are used instead of CRTs, and docking stations and laser printers are discouraged. Energy Star rated equipment has been selected whenever available, and shared use of printers and copiers is maximized.

©Woods Hole Research Center, 2007