Commercial Architecture April 2017 - 20

FEATURE

geothermal hvac
Left. These two pumps move the glycol-water fluid through the 150-borehole field loop.
Middle. Piping from the bore field enters the building in the basement. The overall system is rated at 228 ton of heat-pump capacity
and supports 94 geothermal heat pumps.
Bottom. The dedicated outdoor air system (DOAS) uses an exhaust-recovery-ventilation system. Ductwork from the DOAS runs
hundreds of feet across the rooftop to capture 20,000 cfm of exhaust-fan air, recovering energy that was previously wasted.

tional, providing the airflow but none of the pre-

ing downtime had to be managed to maintain

conditioning (heating and cooling) needed for

occupant comfort. That function was handled

the building. All of these elements had an effect

by BOA president Ron Lower, who acted as on-

on one another in various ways.

site construction manager. Because the DOAS

The solution involved installing:

* a dedicated outdoor air system (DOAS) with
exhaust recovery ventilation

* Aquatherm (Lindon, UT, aquatherm.com) piping to replace the failing steel pipe

* geothermal heat pumps in the common areas
* geothermal circulators with variable-frequency
drives

* a control system to modulate the pumps.

was operational at this point, it was possible to
maintain temperature control to some degree,
even while the common-area and individual
condo GHPs were disconnected. Many common and private-unit GHPs were also replaced
during this stage of the project.
By November 10, most of the building's 86
GHPs were on-line and leak checked. Pipe insulation, controls integration, and several oth-

The BOA agreed to move forward with the

er details became the focus. With the piping

proposal. Extensive due-diligence and negotiat-

replaced, circulators and VFDs installed, and

ing efforts cut the original financial estimate in

most of the GHPs in place, the upgraded build-

half and maximized Federal government and lo-

ing system was fundamentally operational.

cal utility rebates.

The next 40 days were spent adjusting and test-

Replacing the DOAS was the first step. The

ing the system and its controls. The build-

Model ERCH unit, manufactured by Greenheck

ing-compliance

Fan Corp., Schofield, WI, was also fitted with

mid-January 2017.

audit

was

performed

hundreds of feet of ductwork to channel the con-

As the building goes through the first year of

ditioned exhaust air through its exhaust-recovery

operation there will be plenty of opportunities

ventilation (ERV) feature. Brecke Mechanical

to increase energy efficiency by adjusting the

Contractors, Cedar Rapids, made quick work of

building-system controls. Except for the minor

the installation. Though the system was up and

tweaks for energy efficiency, the building is

running in short order, adjustments will continue

ready to serve generations of Bottleworks own-

to be made to the DOAS-which monitors every-

ers without skipping a beat.

thing from outside air conditions to CO2 concen-

One of the residents answered with a re-

trations inside the building-to optimize its per-

sounding "Yes!" when asked if she would seek

formance, energy efficiency, and air quality.

out a geothermal building again. Why? Because

Once the equipment and supplies started ar-

there was no need for outside equipment such as

riving for the upgrades (pipe, GHPs, circulators,

air-conditioning condensers or a cooling tower,

and controls), the work inside the building start-

no boiler, and no combustion heating, which

ed. That was early September 2016, leaving

means no on-site greenhouse-gas emissions. The

slightly less than four months to replace most of

only "noise" is from the super quiet GHPs that

the mechanical systems in the building. Hun-

provide heating and cooling CA

dreds of thousands of dollars in tax credits were
riding on the project being operational by December 31, 2016.
The first stage of the interior work was to replace the piping. Winter was coming and build-

Jay Egg is president and founder of Egg Geothermal, Kissimmee, FL, and a consultant and designer of geothermal
HVAC systems. In addition, he has authored two books
and numerous articles on the subject. He can be reached
at jayegg.geo@gmail.com.

To hear a podcast interview with Jay Egg and see a slideshow of Bottleworks images,
go to commercialarchitecturemagazine.com/1704bottleworks01.

COMMERCI A L A RCHI T EC T URE

APRIL 2017

commercialarchitecturemagazine.com

http://www.aquatherm.com http://www.commercialarchitecturemagazine.com/1704bottleworks01 http://www.commercialarchitecturemagazine.com

Table of Contents for the Digital Edition of Commercial Architecture April 2017