Havtech can provide comprehensive HVAC solutions that include all the major equipment for your project.  This case includes magnetic bearing chillers, vertical riser fan coils, Dedicated Outside Air Systems (DOAS), and Variable Refrigerant Volume (VRV) systems.

Virginia Square Towers

3444 Fairfax Drive, Arlington, VA
Owner: Dittmar Companies
Built: 2014
MEP Engineer: JB Wyble Associates
Contractor: Dittmar Companies

The Challenge
Use a holistic approach to produce luxury high‐rise apartment buildings that have the lowest life‐cycle cost. Nearly 50‐year‐old Dittmar Company builds and holds residential properties—currently 24. Quality workmanship and experience are the hallmarks of this respected firm. Construction, management, and rental activities are all in‐house so Dittmar has complete control of how their buildings are built and operated to minimize life cycle costs. Virginia Square, a dramatic luxury apartment complex at 3444 Fairfax Drive in Arlington, is their latest example.

Rendering of Virginia Square Towers showing second phase behind.

Rendering of Virginia Square Towers showing second phase behind.

The Solution
Dittmar’s HVAC Division Head, Bruce Cormack, and their mechanical engineer, JB Wyble Associates, examined and evaluated new as well as old technologies to come up with a holistic solution incorporating the best the industry has to offer.

Since Dittmar is intimately involved in the design, constructing the building with in‐house personnel, operates, maintains, and manages their properties over the long term, they know the economics and feasibility of all the new technologies. Virginia Square is one of the first registered LEED Gold residential buildings in Arlington County. Since the building is multi‐use it has several different HVAC systems.

The central plant has two Daikin Magnitude magnetic bearing chillers of 250 and 350 tons. The unequal sizes were used so that the smaller chiller could unload down to the anticipated minimum load of about 12‐1/2 tons. Additionally, the mix match combination allowed the chillers to qualify for LEED

Two Daikin Magnitude oil‐free centrifugal chillers are installed in a very compact equipment room. Note the marine water boxes on the condensers to facilitate tube cleaning.

Two Daikin Magnitude oil‐free centrifugal chillers are installed in a very compact equipment room. Note the marine water boxes on the condensers to facilitate tube cleaning.

EAc4 points. The heating side is comprised of 5‐97% efficient condensing modular boilers that can be controlled in various combinations to produce heating water or domestic hot water. The residential areas use a 4‐pipe stack fan coil system with optional sound package and with EC motors providing significant energy savings of old‐technology PSC motors. Control of ventilation air is complicated and can be very wasteful of energy in high rise residential buildings.

This building has separate systems to allow for 60 CFM toilet exhaust, 110 CFM microwave, and 140 CFM of dryer exhaust on separate risers using pressure demand‐control to maintain air balance and maximize efficiency. Dedicated Outdoor Air Systems use AAON packaged rooftop units with energy wheels (where possible) VFD‐controlled fans, and hot gas reheat for separate and precise control of sensible and latent loads. The rooftops were furnished with factory mounted Reliable controls, Dittmar’s chosen controls vendor.

AAON Dedicated Outdoor Air System (DOAS) units individually supply and control fresh air to toilet , microwave, and dryer ventilation system.

AAON Dedicated Outdoor Air System (DOAS) units individually supply and control fresh air to toilet , microwave, and dryer ventilation system.

The ground floor is comprised of retail spaces using individual Daikin vertical ducted water source heat pumps. This provides maximum flexibility and easy individual utility billing. There is also a Daikin water cooled VRV system conditioning an enclosed passage between the North and South buildings.

Dittmar and JB Wyble have taken advantage of ECM and VFD modulation technologies to demand‐ control just about every medium in the building including garage exhaust, water pumping, ventilation,

The dramatic lobby exemplifies the luxury level of Virginia Square Towers.

The dramatic lobby exemplifies the luxury level of Virginia Square Towers.

heating, and cooling. Modulation results in cubic savings. A reduction in speed (load) of 1/2 results in an energy reduction of 87.5% (1/2 x 1/2 x 1/2 = 1/8). The result of all this careful analysis and investment in quality features and energy saving technologies is a building that will profitably contribute to the Dittmar portfolio for years to come.

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