No matter how well an HVAC system is maintained, it will
eventually need to be replaced. That isn’t a task to be entered into lightly.
HVAC system replacement is a costly and messy process that can disrupt building
operations over an extended period of time. It’s crucial to ensure that the
retrofit produces the maximum benefit. Not only will this enhance the operation
of the facility, it will also help to ensure that the retrofit process will not
have to be repeated in the near future.
Facility executives embarking on an HVAC retrofit should
keep eight factors in mind.
1. In-kind
Replacement
The easiest and quickest way to replace an older HVAC system
is to put in a new system that matches the old one. While that approach is
simple and quick, it is often not the best choice. Most HVAC systems and their
components have normal service lives of 15 to 25 years if properly maintained.
When a system is originally installed, it is sized and designed to meet the
needs of the building at that time. But buildings change, and so do the
operations that take place within the buildings. There might be more people in
the building and more electronic equipment -- computers, printers, copiers and
the like. Simply replacing in kind does not take these changes into
consideration. To get the most out of HVAC system retrofits, the new system
with new options must be designed to match the current needs of the facility.
2. New Technologies
HVAC technology has achieved tremendous progress in the past
15 years. New DDC control systems provide a better climate while reducing
energy costs. High-efficiency or alternative-fuel chillers can reduce the cost
of air conditioning. Variable frequency drives can improve the operating efficiency
of both chillers and fan systems. Interoperable building automation systems
give facility executives the tools they need to better manage operations. An
HVAC retrofit is often a good time to take advantage of these newer HVAC
technologies.
3. Flexibility
Buildings today are in a constant state of churn. Interiors
are rearranged. Old tenants move out and new ones move in. Infrastructure
requirements increase. The result is that facility executives are constantly
changing facilities to meet the needs of occupants. But one thing that doesn’t
change easily in many existing buildings is the HVAC system. That’s why flexibility should be a key goal
of HVAC system retrofits. HVAC systems should be able to adapt to those changes
without requiring costly alterations. Otherwise, facility executives face a
no-win situation: covering the cost of expensive changes to the HVAC system or
living with an HVAC system that can’t keep up with changes in the building.
4. Part-load
Performance
Chillers are the single largest users of electricity in
practically all buildings. When selecting replacement chillers, much emphasis
is paid to this full-load efficiency rating. But that’s only part of the
picture. Most chillers operate at full
load for less than 5 percent of their total run time. The other 95 percent of
the time chillers are operating below full-load capabilities. As the load on
chillers decreases, so does the efficiency of the units. Because chillers operate under part-load
conditions for such a high percentage of their run times, the annual energy
cost of the chiller will be determined primarily by its part-load efficiency.
Although it might cost more to purchase a unit with better part-load
efficiency, this premium will be recovered many times over through energy
savings during the life of the chiller.
5. Maintenance
As HVAC systems age, maintenance requirements increase. But
as long as a system doesn’t stop working, it might not even be considered as a
retrofit candidate. But just because a system is able to limp along doesn’t
mean it’s operating efficiently or meeting the requirements of the application. Look through maintenance records for the
building. High maintenance costs and increasing maintenance requirements are an
indication that those systems or components might be approaching the end of
their service lives. Facility executives should set priorities for HVAC
retrofits based in part on maintenance requirements.
6. The Big Picture
There is a tendency when planning for HVAC retrofits to
develop tunnel vision and focus on only a specific component or portion of the
HVAC system. The chiller that is becoming unreliable or the air handler that no
longer meets the needs of the conditioned space might be serious problems that
demand to be addressed. But before making retrofit decisions, facility
executives should step back and determine if other projects planned for the
building will affect HVAC system operation.
For example, upgrading the lighting system or installing more
energy-efficient windows will reduce cooling loads. If those projects are
planned in the near future, then a planned retrofit program for the building’s
chiller should be scheduled after they have been completed. Reduced cooling
loads will allow a smaller chiller, reducing both first and operating costs.
7. Building Occupants
One of the goals of any HVAC retrofit program is to improve
the level of service. While facility executives might understand the technical
problems with the existing HVAC systems, they will not fully comprehend the
needs of building occupants unless they get them involved in the retrofit
process. After all, occupants are the ones that understand their operations the
best. Facility executives will not know what system will best meet occupant
needs -- indeed, they might not even have a good understanding of what their
HVAC needs are -- but occupant input will give the facility executive a clearer
understanding of what the HVAC system will be expected to do. Building occupants are also good sources of
information on the performance of existing systems. Frequently, they are aware
of problems that go unreported to building staff. That information is often
crucial in setting priorities for HVAC system retrofits.
8. Program Approval
HVAC retrofits must compete with other programs for funding.
Too often, though, facility executives simply submit funding requests with
little or no supporting information. As a result, projects fail to win the
funding needed to perform a complete retrofit. Instead, components are patched
together just to keep the system running.
To increase the chances of receiving funding, facility executives must
submit their budget requests in a format familiar to financial managers. Energy
savings, maintenance savings, return on investment: These are among the terms
that will help convince financial managers of the value of the project. It’s also important to provide the right
level of detail. For example, if reliability is an issue, it isn’t enough
simply to report that fact; instead, the facility executive must show that it
is a problem with key supporting information. How many times has service been
interrupted? What was the cost of those interruptions to the maintenance
department? What was the cost to building occupants? What level of performance
can be expected from the retrofit system?
An HVAC retrofit is a major undertaking for the facility
department, the occupants and the organization’s management. It is also an
opportunity -- an opportunity that, because of the cost and disruption
involved, might not come along again for decades. What’s more, the success of
the project will shape the way that occupants and top management perceive the
facility department -- a perception that will influence the success of future
facility initiatives. Taking the time to get the retrofit right is worth the
effort.
Gehringer Mechanical
offers plumbing, heating, air conditioning, and electrical work to customers in
Berks, Bucks, Chester, Lehigh, and Montgomery Counties.
