Reston Station OB 1

Reston Station OB 1

Reston, VA

Contract Value: $9,255,000

GC: James G Davis Construction

Owner: Comstock

Engineer: GHT Chartered

Project Description

Reston Office Building 1 is a 16 story concrete office located at the intersection of the Dulles Toll Road and Wiehle Avenue. Reston OB 1 has the distinction of having the floor plate increase in size at each level making it wider at the top than at the bottom. Additionally, it features an exposed concrete exoskeleton that adds to its unique appearance.

The Building Mechanical System is a DOAS VAV type system. In this application high temp chilled water (56 degrees) is fed to chilled water coils at each VAV box. These boxes are all sensible cooling and give additional cooling control at the individual level. This type of system is also defined by dry cool air from the Energy Recovery Units that feed dehumidified cold outside air directly to the primary inlet of the VAV boxes. This type of system removes typical floor air handling units and reduces the size of a typical floor duct loop that are common in traditional office buildings. Due to higher temperature of the chilled water and the dehumidification done at the energy recovery units there is no need for condensate piping from the Chilled Water Coils at the VAV boxes.

This system employed two 30,500 CFM energy recovery units feeding the outside air to 160 DOAS Boxes with electric heat on each floor. The Chilled Water System used a three chiller configuration to produce traditional 42 degree chilled water. This Chilled Water system fed the ERU’s with traditional water temperature with the remaining Chilled Water load “mixing” through a Heat Exchanger to produce the higher temp 56 degree Chilled Water that fed the typical floor loops. The system utilizes 15 base mounted pumps to move the two different chilled water temperatures (one for the DOAS boxes on the floors and one for the coils in the ERUs) and condenser water through the building.

The Main Lobby is fed by its own water-cooled AHU and also employs a hydronically heated slab edge on the interior at the base of the floor to ceiling glass to control condensation. The 2nd floor also has a separate water-cooled AHU that serves the exercise room and shower room area provided as an amenity for the tenants. The typical bathroom groups were fed by way of multiple PRV stations on a few of the floors that were the points of distribution for multiple floors each. Domestic Hot Water and Recirculation were accomplished via water heater rooms that fed 3 to 4 floors each. Mallick was also responsible for installing a 6” stainless steel Storm Riser to the upper roof that would be a drain for a proposed future helipad.

One of the logistical challenges was to deliver the multiple sections of the Energy Recovery Units to the Penthouse Level prior to pouring the roof and protecting them from the remainder of the structural concrete work. This allowed them to be assembled and set as soon as the structural work was completed. There also were the usual sequencing challenges that were met by pre-fabricating the pipe loops and bathroom groups for each floor and timing the material to be delivered and installed immediately after re-shores were removed.

With the Central Plant located at the Penthouse Level it became critical path to getting the Building completed. Mallick worked with Davis Construction and the other Subcontractors to sequence out the installation of the Central Plant in 6 phases with high and low installation scheduled out by Subcontractor to ensure optimization of workflow. This, coupled with the Prefabrication of the plant’s major components, allowed the entire Construction Team to meet the dates for assembling the Plant and getting the system started up.

Through in-depth planning and constant communication with Davis Construction and our fellow subcontractors Mallick delivered the project on-time. Mallick is proud to be associated with this unique addition to the burgeoning Reston skyline.