Case #1

Main Problem

Low temperature difference across chilled water systems, high energy consumption in the central chilled water plant, old gas engine-driven chillers piped in series configuration.


The approximately 40-story building had a perimeter induction air system with intermediate heat exchangers on several floors. The heat exchangers were served by the central chilled water plant and had three-way modulating valves to control the secondary leaving water temperature. To learn the real cooling load profile on the building, we took several steps:

  • installed the front end of a building automation system
  • installed high accuraccy temperature sensors and flow meter in the chilled water supply and returns
  • wrote equations to calculate the tonnage on the building
  • performed load calculations to include "load diversity"

By logging tonnage, supply and return chilled water temperature, and chilled water flow rate over an extended period of time, we were able to correctly redesign the central chilled water plant. IES founder Steve Griffin's experience engineering for a large manufacturer gave him particular insight into the part load characteristics and selection of centrifugal chillers.

Key aspects of the redesign resulted in an estimated energy savings of about $50,000 per year:

  • pre-piping of the chiller plant
  • changing the valves on the intermediate heat exchangers
  • the installation of a new 1000-ton high efficiency chiller
  • changing to variable-flow systems to eliminate a 100 HP pump

The variable pumping system and high efficiency chiller solved the low temperature difference of the chilled water system and substantially reduced the operating cost of the plant. As part of the design and installation, the control system was extended to critical portions of the system so that after installation, the system could be monitored, trended, and optimized.

The commissioning and optimization part of the project was crucial. Although the empirical data was gathered up front, it was important to optimize the central plant after the installation process. The commissioning process not only helped in monitoring and controlling all the design parameters but also addressed operational events after installation.

Case #2

Main Problem

Aging 20-plus story office building with inefficient centrifugal chillers. Low differential temperatures were occurring in a chilled water distribution system. The building housed the computer facility for a major national firm. Operation and back-up cooling capabilities were of utmost importance.


We studied the water side operation and energy consumption, and also the overall building energy consumption. Although the envelope of the building was modeled, no changes to the walls or glass were to occur. High-efficiency lighting systems were also modeled, and we accounted for their effect on the airside portion of the air conditioning in the redesigned chiller plant and chilled water delivery system. Multiple chiller selections were made to fit the specific energy profile of the building. The project design included:

  • replacing two 850-ton chillers
  • re-piping the chiller plant to a different piping strategy
  • replacing the cooling tower
  • installing a buiding automation system

One of the requirements that made this project interesting was that the building’s data center (~200 tons) needed uninterrupted cooling. The building itself could only be without cooling over a four-day weekend.

The owners realized substantial energy savings from chiller, pumping, lighting, and other energy modifications. New operating strategies were developed that allowed for substantial “part-load” chiller energy savings. Post-construction commissioning and optimization was part of this project as well.

Case #3

Main Problem

Chronic failure of first stage compressors at multiple systems of a large LifeCare Center (assisted-living facility buildings) and severe condensation associated with the air handlers.


Following the repeated failure of multiple first-stage compressors of the air conditioning system, we were hired by the legal team of the building owners to discover the cause of the problem. A “tear down” analysis of the compressors confirmed liquid dilution. After an exhaustive investigation that included many interviews, IES determined that several refrigerant management issues were involved:

  • long line lengths
  • misapplied hot gas by-pass (HGBP)
  • lack of liquid line solenoid valves
  • oversized expansion valves

The oversized thermal expansion valves resulted in “hunting” and overfeeding, creating uncontrollable superheat for the units. During the OFF cycle, migration of the liquid occurred to the un-insulated hot gas and suction line buried underground.

The condensation on the air handler cabinetry was caused by a condensate drain issue which resulted in moisture in the internal insulation between the double wall metal panels of the air handler. Once the insulation is wet, a loss of insulating value occurs, resulting in a drop in the surface temperature on the exterior of the unit and creating condensation.

Case #4

Main Problem

Mold growth on the walls and ceilings of the top level of a multi-story oceanfront home.


The home had substantial mold growth on the ceiling, around the light fixtures (“star-burst” pattern), and around the hurricane shutters access panel. Air infiltration was occurring through the improperly sealed shutters and via the unconditioned attic space. The top two stories of the 8-level home were served by an air-conditioning system with a "zoning system."

IES performed pressure differential tests and learned that the air conditioning system created negative pressurization of the top level that encouraged infiltration of outside air. This air interacted with the cold surfaces of the conditioned space, causing mold growth. Once mold remediation was performed per IES guidelines, a new HVAC design and an unventilated attic were created by IES to eliminate pressure imbalances and to control the dew point of the attic.

Case #5

Main Problem

Mold growth in multiple locations of a Children’s Care Hospice due to flashing issues and other water intrusion problems.


Improper roof and wall flashing at multiple locations caused water leakage especially during wind-driven rains, leading to mold growth in multiple parts of the building. Failure of the waterproofing membrane along the planters also caused mold growth issues on the interior walls in some locations.

IES provided a detailed scope of work for all the involved contractors to eliminate water intrusion issues:

  • mold remediator
  • put-back contractor
  • landscaping architect
  • mechanical contractors
  • plumbing contractors

IES also assisted the owner throughout the coordination of this work. Remediation protocol involved containment design, removal and cleaning as per EPA Guideline 402-K-01-001 and IICRC-S520.

We recommended using primary and secondary negative pressure containment areas due to the critical nature of the facility, and we implemented the project in two phases to ensure unhindered operation of the facility.

Case #6

Main Problem

Mold growth occurring in a commercial facility (car dealership).


Condensation of warm moist air was occurring on the cool surfaces of the air conditioning system. The parts warehouse exhaust fans created negative pressure, and the high moisture content air was drawn into the space above the ceiling plane in the office area and into the conditioned space. The negative pressure was “pulling” moisture-laden air around the light switches and electrical outlets and creating surface smearing.

Mold spores and dust were controlled by installing filters with good small particle efficiency, eliminating the majority of mold spores and dust from the air system. To do this correctly, we made sure that unfiltered air did not enter the air handler cabinetry. Mold remediation protocol that adhered to the recommended guidelines was furnished to the contractors, and IES redesigned the complete HVAC system and made building envelope changes to resolve the problems.

Case #7

Main Problem

Floor moisture problems and related odor issues in a residence forcing owners to vacate.


Unpleasant odor was causing severe discomfort for the owners, but there were no conspicuous signs of mold growth. After removing a small test area, IES discovered mold growth on the padding between the wood floors and the concrete slab. IES performed the ASTM-F2170 test and confirmed high moisture conditions in the concrete.

A section of the slab was cut open for inspection, revealing a failed vapor retarder. IES suggested new cleaning procedures and through research, found an auxiliary vapor retarder to go on top of the concrete slab. An auxiliary dehumidification system was designed to draw outside air into the home. Special attention was given to the slab underneath the bottom plate of a vulnerable closet wall. The owners had the wood floors reinstalled, and have not had any indoor air quality complaint since the repair.

Case #8

Main Problem

To research and help a large national company prepare their commercial facilities against the avian/pandemic flu.


IES performed exhaustive research to help a large national company protect its buildings’ workforce and minimize absenteeism in the event of a pandemic/avian flu. We compiled a detailed study of disease-causing pathogens (fungi, bacteria and viruses), including their relative sizes and the most common mechanism of dissemination. This allowed us to design the most optimum capture/kill methodology in the facility and the air conditioning system.

IES developed a strategy that offered various engineering control options, and we compared the effectiveness of natural ventilation with several air conditioning equipment related controls:

  • Ultra Violet Germicidal Irradiation (UVGI)
  • Electrostatic air purification
  • HEPA and other filtration methods
  • Infrared screening

As part of the report, actual curves comparing different technologies to control the pathogens were furnished, and we also recommended near-field control methods and other necessary administrative controls and policies required to deal with a potential health crisis.

A favorable balance between demand and consumption
Solutions that Effectively Lower Consumption and Demand
Enhanced safety & comfort throught proper energy management
  • A favorable balance between demand and consumption
  • Solutions that Effectively Lower Consumption and Demand
  • Enhanced safety & comfort throught proper energy management