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From Conception to Reception: Lessons Learned from the New ASHRAE HQ

From Conception to Reception: Lessons Learned from the New ASHRAE HQ

From ASHRAE Journal Newsletter, Feb. 10, 2021

Converting a building built in the 1970s into a net zero ready facility can be done. The new ASHRAE Headquarters is proof of that.

Today during the Virtual Winter Conference, engineers and architects who helped facilitate the renovation of the new ASHRAE HQ will take the audience from finding a suitable building through completion of this highly visible project. The live session, ASHRAE HQ: From Conception to Reception , is scheduled to start at 3 p.m. Eastern. It will include a Live Q&A.

Seminar chair Dennis Wessel, P.E., Fellow/Life Member ASHRAE, member of the ASHRAE HQ Building Technical Advisory Subcommittee, and Stanton Stafford, P.E., Member ASHRAE, the design engineer for the HQ HVAC system, talked with ASHRAE Journal about the new HQ’s features as well as lessons they learned from working on the new HQ.

1. What sets the new ASHRAE HQ apart from other large commercial buildings?

Stafford: The new ASHRAE Headquarters is the first net zero energy ready commercial office renovation in Georgia, if not in the southeastern United States. The building demonstrates that cost-effective, healthy, high-performance transformation of our aging building stock is possible even in hot, humid climates.

Wessel: Most net zero buildings are done as new construction. This building is a renovation of a building that was originally constructed in the late 1970s—when very early attempts at energy conservation, which were the result of the early 1970s oil embargo, were frequently less than effective at energy reduction. The current renovation has created a very low-energy consuming building, permitting the use of photovoltaics to offset the purchase of electricity on an annual basis. 

2. What are some features that makes the new HQ innovative?

Stafford: ASHRAE’s owner’s project requirements (OPR) document established performance-based targets around energy use, daylighting, plug load and lighting demand and acoustics, in addition to prescriptive requirements relative to ASHRAE standards compliance. 

An iterative, modeling-centric process was leveraged to inform design team decisions relative to passive (envelope, shading and daylighting) and active (lighting and HVAC) strategies geared toward OPR compliance. A few building elements represent innovations for Climate Zone 3A and the low-rise office renovation typology: 

  • Design of glazing dimensions, skylights and shading devices to achieve spatial daylight autonomy in 55% of occupied spaces while minimizing solar heat gain and glare in the building.
  • Integration of high volume-low speed (HVLS) fans throughout the office space to expand the range of ANSI/ASHRAE Standard 55– 2017, Thermal Environmental Conditions for Human Occupancy, and improve the efficiency of the radiant panels through air movement.
  • Use of radiant panels for building heating and cooling.
  • Control of thermal comfort involving sequential deployment of three independent systems: packaged dedicated outdoor air units, HVLS fans and radiant panels.
  • Focus on improved cognitive performance of building occupants through displacement ventilation coupled with radiant panels in high-occupancy spaces.

Wessel: [Innovative features include:]

  • The use of a dedicated outdoor air system (DOAS) to supply 30% more outdoor air than dictated as "minimum" by ANSI/ASHRAE Standard 62.1– 2019, Ventilation for Acceptable Indoor Air Quality.
  • The use of radiant panels for both heating and cooling of individual spaces throughout the building.
  • The use of a heat recovery chiller to provide all heating and cooling water for building conditioning.
  • The use of six-way control valves to control hot and chilled water to radiant panels.
  • The building takes best advantage of Standard 55–2017 by using temperature and relative humidity levels that are beyond what many would consider optimum comfort levels. This is accomplished by using ceiling fans to increase air velocities on occupants, maintaining occupant comfort at elevated temperatures and relative humidity levels.

3. What lessons, facts and/or guidance can an engineer working in the field take away from this project?

Stafford: The building envelope is the most critical system in a high-performance office building.

It was understood from the beginning that ASHRAE’s energy use intensity (EUI) goal of 21.4 kBtu/ft2·yr (243 MJ/m2·yr)* was going to require a heavy focus on envelope interventions, as blower door testing and thermal scans of the façade revealed a leaky and thermally unbroken circa-1970s building. Without a high-performance envelope, there was no way optimization of lighting, HVAC systems and advanced plug load control could meet the OPR’s energy and daylighting goals.

Through schematic design-level modeling, window-to-wall ratio, glazing dimension and shading depth were optimized for first cost, energy and daylighting performance. Additionally, envelope sensitivity analysis allowed for best-value decision-making relative to envelope performance criteria (e.g., glazing U-value and SHGC, wall and roof R-value modeled to determine the point of diminishing return).

 *For reference, Climate Zone 3A’s benchmark EUI is 58 kBtu/ft2·yr (659 MJ/m2·yr)  for office buildings.

4. How will the new HQ further the industry’s knowledge of designing/retrofitting energy-efficient commercial buildings?

Stafford: With a good envelope, top-tier building energy performance can be achieved using a simple, cost-effective, near market-rate HVAC solution.

Early in the design process, ASHRAE and the design and construction teams studied multiple HVAC strategies to “zero in” (pun intended) on schemes that would meet both ASHRAE’s OPR and budgetary goals. With a high-performance envelope design in play, ASHRAE and the design team narrowed HVAC systems down to two schemes for further study:

  •  Scheme 1: Thermodynamically zoned, packaged rooftop units coupled with packaged dedicated outdoor air systems.
  •  Scheme 2: Radiant heating/cooling panels coupled with an air-cooled, heat pump chiller.

Building energy modeling showed that both schemes exceeded ASHRAE’s EUI goal. Scheme 1 showed the higher EUI at ~20 kBtu/ft2·yr (227 MJ/m2·yr); the Scheme 2 model came in at ~17 kBtu/ft2·yr (191 MJ/m2·yr).

Contractor pricing of the two systems, however, showed that Scheme 2 was over 2 times the first cost of Scheme 1. Based on industry data, Scheme 1’s HVAC system first cost fell close to the regional average cost for HVAC in comparably sized office buildings. Scheme 2 was ultimately chosen based on variables other than first cost, but the system evaluation process opened a lot of eyes relative to what is possible through creative use of more conventional HVAC systems.

Wessel: [The new HQ helps the industry understand:]

  • how best to improve the efficiency of the 1970s-vintage building envelope by investigating multiple options on possible changes to window-to-wall ratios and various insulation options;
  • how the use of energy consumption analysis programs can be used effectively to investigate design options; and
  • how the use of blower door leakage studies to aid in the determination of building tightness and air leakage points.   

5. Were there any surprises or unforeseen challenges for you while working on the new HQ?

Stafford: SAs selective demolition uncovered existing conditions that were previously concealed. There were a few items relative to infrastructure upgrades (e.g. plumbing piping plus electrical gear/conduit replacement) that presented challenges to aligning construction budget with ASHRAE’s goals. The site constraints also limited construction cost feasibility of certain envelope interventions and system options.

Additionally, accurately cost estimating the Scheme 2 HVAC concept was difficult given the Atlanta contractor market’s being largely unfamiliar with the system. Multiple meetings were required to educate the contracting team on the function and requirements of the system which, ultimately, brought the HVAC system cost down a good amount.

Wessel: Building leakage, which was identified as average by the blower door test, was an unexpected benefit because the building was expected to be much more leaky.

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