Capital Planning for a Midwest Office Complex
The Problem:
 Chelsea
Group was requested by the owner of a twenty-seven story high rise office
building, originally constructed in the 1970’s, to review in detail all of the
mechanical projects identified in their 5-year capital expense budget.
Approximately 20 different improvements were anticipated, but the owner desired
an independent review of the projects listed by their property management firm
for appropriateness and cost justification. Chelsea Group also took on a
significant role in technical oversight of the improvements, including
verification of proper installation and performance.
These projects included such improvements as:
- Install new building-wide computerized energy management system
- Inspect supply duct lining for condition and recommend action plan for
addressing degraded liner
- Re-vamp existing air handling systems serving the lobby area to offset
winter infiltration through lobby doors
- Inspect and recommend repair or replacement of existing cooling towers
- Address the magnitude of the tenant-owned cooling package units for
potential sub-metering or lease adjustments
- Evaluate variable speed chilled water pumping
Chelsea Group Intervention:
BUILDING-WIDE COMPUTERIZED ENERGY MANAGEMENT SYSTEM (EMS)
Over $2 million was invested in the installation of a new EMS for the building.
As a project close-out item prior to final payment to the installation
contractor, the owner asked Chelsea Group to review:
- Sequences of operation
- As-built drawings
- Installed hardware
After discovering many omissions from the as-built documentation, Chelsea Group
revised sequences to optimize energy conservation.
Immediate results: The review saved more than one hundred of
thousand dollars in annual electrical costs by refining the operating
sequences of the typical floor air handling systems.
 SUPPLY
DUCT LINING
Tenants observed particulate matter dropping out of diffusers in their offices.
Preliminary review revealed previous microbial non-viable growth on the duct
liner, which had desiccated over time. After carrying out a complete survey of
all 50 air handling systems in the building to establish existing conditions,
Chelsea Group recommended a prioritized list of systems to be re-lined.
Immediate results: Re-lining the ducts has overcome the original
problem, and tenants are no longer concerned over particulate deposition.
RE-VAMPING OF EXISTING AIR HANDLING SYSTEMS
In cold climates tall buildings tend to act like a chimney,
sucking in cold air at the lower levels and pushing warm air to the top. In this
building, that effect was bringing in cold outdoor air into the entry lobby.
Chelsea Group recommended modifications of the air handling systems to introduce
larger amounts of conditioned outdoor air, and additional heating capacity to
those systems to positively pressurize the lobby with warm air.
Immediate results: The pressurized lobby will prevent bitter cold
outdoor air from entering the lobby during winter conditions, making the lobby
much more comfortable.
INSPECT AND RECOMMEND REPAIR OR REPLACEMENT OF EXISTING COOLING TOWERS
The existing cooling towers had been “band-aided” for a number of years, and
were at the end of their useful service life. The owner wanted to know if the
life of the towers could be prolonged by another 5 years or whether replacement
was necessary.
 Chelsea
Group’s inspection found:
- Leakage of condenser water
- Increasing maintenance needs
- Inefficient and costly cooling system operation
Chelsea Group recommended replacement of these towers by airlift from the top
of the building.
Immediate results: The new cooling towers will reduce make-up water,
require minimal maintenance, and improve overall system efficiency.
TENANT-OWNED COOLING PACKAGE UNITS
Many tenants had installed their own packaged air conditioning systems,
primarily to cool computer rooms. The owner desired an approach for assessing
the energy cost impact of these systems and a method to assess that cost to the
respective tenants, even though the electrical systems are not sub-metered.
Chelsea Group developed an approach for establishing tenant billing on the
basis of measured amperage of each system for fan energy, and a British thermal
unit (Btu) meter for quantifying electrical energy requirements for cooling. The
Btu meter for each tenant is read on a monthly basis, and a line item on the
monthly lease invoice reflects this additional energy charge.
Immediate results: By providing a method to measure additional
energy use by some tenants, Chelsea Group helped the owner realize significant
energy cost savings. Accounting for the tenant energy consumption enables the
owner to charge back the energy costs to the tenants with the packaged cooling
systems, as a result not penalizing the tenants without cooling packages.
 VARIABLE
SPEED CHILLED WATER PUMPING
The existing chiller plant utilizes constant speed circulation pumps. Chelsea
Group evaluated the potential energy cost savings of converting the constant
speed pumping arrangement to a variable speed system.
Chelsea Group determined that the project was cost-justified because only
minor piping revisions were needed and because two-way valves already existed at
the cooling coils of the air handling systems.
Immediate results: Based on Chelsea Group’s recommendation,
conversion of the pumps to a variable speed system is underway. When the
project is complete the owner will benefit from:
- Improved energy efficiency, with the ability to run a pump at part speed
as opposed to full speed all the time
- Improved indoor air quality by providing continuous dehumidification
during cooling season
- Operational flexibility to simplify maintenance schedules, and respond to
tenant changes
Final Results:
Chelsea Group helped the owner review and justify expenditures on necessary
mechanical projects. Chelsea Group provided the owner of this building with:
- Substantial energy cost savings
- Technical review of building systems and documentation
- Impartial third party review of contracted work
- Mechanical system, ventilation, and building envelope expertise
- Means to address tenant needs
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