Dwyer Engineering Blog

Office Building VAV Rooftop Unit Replacement

Posted by Dave Driver, PE Feb 9, 2016 5:41:08 PM


VAV Replacement Pitfalls

When the time comes to replace that old VAV rooftop unit, a building owner may solicit proposals from contractors for more efficient, but same capacity, direct replacement equipment.  

Before signing that purchase order, here are four considerations that could justify a more in-depth look. 

  • Is the capacity right?
  • Is the new unit heavier?
  • Does the new unit fit?
  • Is gas available?
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Topics: Washington-DC, Rooftop Units, Office Building HVAC

Energy Code – Restaurants & Daylighting Controls 

Posted by Brian Davis, PE, CEM Sep 3, 2015 3:35:09 PM

How do you incorporate the mandatory daylight dimming requirements of the 2012 International Energy Conservation Code for fine dining restaurants? 

Fine Dining restaurants are notable in the way that lighting is carefully controlled to obtain the desired atmosphere.   These restaurants require subtly different lighting levels throughout the day.  Programmed dimmers are used to provide a variety of soft lighting looks for meals.   The 2012 International Energy Conservation Code (IECC) requires daylighting zones for all commercial spaces, however, making ambiance difficult to control in fine restaurants.  

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Humidity Solutions for Retail HVAC

Posted by Dave Driver, PE May 21, 2014 6:30:00 AM

5 Ways to Control Humidity with Small HVAC Systems

Owners of retail shopping centers and other commercial buildings want long lasting, inexpensive HVAC equipment that can be on site in three or four weeks and can be maintained by a local service contractor. Enter the constant volume direct expansion (DX) air conditioning system, most commonly the small packaged rooftop unit and its partner in crime, the split system. Unfortunately, these systems won’t control indoor humidity in summer months unless your mechanical engineers take important precautions during design.   If you lose humidity control in your store or office, odors develop, turning off customers, and everyone feels sticky even if it is cool inside. We have five steps to prevent this. 

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Topics: Split-Systems, Retail HVAC, Humidity Control, Rooftop Units

DC Green Building Code

Posted by Matthew Dwyer Apr 24, 2014 9:43:00 AM

The new DC Green Building Code took effect as of April 2014, based on the 2012 International Codes (access ICC here: http://publicecodes.cyberregs.com/icod/index.htm) and intended to increase energy conservation in the nation's capital.  There are 14 separate Word files of amendments (650+ pages) available for free at dcra.dc.gov, or if you want a single, very unofficial, bookmarked pdf of the amendments, let me know.  Three amendments caught my eye on my first read:

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Topics: Washington-DC, Energy, Building Codes, green engineering


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