1100 Vermont Avenue, N.W.
Washington, D.C.
General Contractor: Advanced Design & Construction Company
Architect: Morgan Gick McBeath & Associates
Engineer: META Engineers, P.C.
Contract Amount: $3,505,097.00
Start Date: 01/13/2012
Completion Date: 5/30/2013
Challenges
Shapiro & Duncan’s scope of work for this 12-story core and shell office building renovation included design and installation of HVAC and plumbing, with active chilled beams being the primary source for heating and cooling. Using a four-pipe system (two cooling and two heating) with mechanical risers and loops throughout the building, the chilled beams are able to heat or cool each space on demand. This is an advanced mechanical system design that is unique for office buildings in the Washington, D.C. market.
Shapiro & Duncan’s project team faced a number of challenges on this project, but was able to work through all of these issues with the great team effort of our CAD department, office and field crew. When work began on this project, we planned on following the design documents and re-using all the existing shafts and penetrations for routing our mechanical and plumbing pipe. However, after getting on site and laying out the work for this project, we discovered that the pre-existing penetrations were not sufficient for the number of pipes that had to go through the floors.
When we approached the design team with this issue, we were instructed to core drill the needed holes without disturbing the rebar hidden within the slabs. This was no easy task, as 200+ additional holes were needed to make the system work. Through weeks of coordination and the use of Ground Penetrating Radar (GPR), we were able to move forward with 90% of the holes and not disturb the existing rebar. The remaining 10% of holes had to be reinforced with carbon fiber matting epoxied to the deck.
While these core drilling issues were going on, our CAD team had begun their coordination of the mechanical penthouse where all the large equipment is located. Shapiro & Duncan has put together some tight mechanical rooms before, but this mechanical room turned out to be the tightest mechanical room we have ever completed. Through careful measurement and weeks of coordination by our CAD team, we were finally able to fit all the equipment shown on the contract documents into our model. Thanks to our CAD team’s previous experiences on other projects, we were able to get all the equipment in the penthouse coordinated to maintain proper access for maintenance and future large repairs.
Solution
Installed equipment included:
- AAON outdoor energy recovery unit (OAU-1) with cooling/heating and recovery wheel;
- McQuay Vision indoor air handler (AHU-1);
- McQuay chiller (CH-1);
- Two Lochinvar condensing boilers (B-1 & B-2);
- Bell & Gossett pumps;
- Greenheck return fan (RF-1); and
- 74 Dadanco core and shell chilled beams.
In the cooling sequence, RF-1 brings return air (and fresh air from the outside via the outside air damper) from all of the typical floors up into OAU-1 for stage 1 conditioning of the return air. The air is then sent to the large AHU-1 for the second stage of cooling (chilled water being supplied by the chiller). The system is able to remove all the latent heat from the return air after it travels through the first two stages of cooling on the penthouse level. AHU-1 then sends the air down the main exterior supply duct back to the typical floors. There, the air is tempered a third time via the chilled beams which are fed chilled water as well. Since the latent heat is removed from the air prior to getting to the chilled beams, Shapiro & Duncan’s solution eliminates the need for drains on the chilled beams. All the removed condensate water is ejected from OAU-1 and AHU-1 inside the penthouse.
The heating cycle is similar to the cooling cycle. RF-1 brings the return air through OAU-1 for its first stage of heating (by electric heat). Then it enters AHU-1 for second stage heating. Finally, return air is sent back down to the chilled beams for its final tempering before being ejected into the space.
Result
The overall project was a great success. Shapiro & Duncan’s project team encountered several complex issues, but we were able to tackle these head on and keep the project moving at a steady pace. There are only a few buildings in the Greater Washington DC market with such an advanced chilled beam design, and Shapiro & Duncan is proud to say that we played the major role in putting this one together.
