HVAC Improvements For Existing Buildings – HVAC Retrofits

One way to identify tenant needs in existing buildings is to note what architects and designers are trying to create for clients in new buildings. The objective for a new building is to provide the ideal office space. Tenants are often looking for space that can address such issues as flexibility, modular space planning, environmental considerations and individual temperature comfort. A particular hot spot for many national tenants is to gain the highest level of productivity from their employees. This usually means the building will need plenty of HVAC zones, flexible office hours and point-of-use supplemental systems. These factors point to a flexible and often programmable HVAC system that can meet tenants' needs.

Architectural trends can also create new loads and requirements for an HVAC system in an existing facility. More natural light can increase heat loads; atrium designs can obstruct air distribution; additional zones can increase the overall volume of ventilated air needed, the quantity of heat to be rejected and the amount of outdoor air required. If a building doesn't have a flexible HVAC plant, then modifications or upgrades to the HVAC system will be necessary to compete with new building design and technology.

One factor that must be considered in any analysis of a possible retrofit is that an HVAC upgrade usually means that the building has to be brought into compliance with current codes. Some codes are based on prescriptive regulations; however, the trend to create a safer and healthier indoor environment can also bring new performance requirements. For example, over time, the percentage of outdoor air has gradually been increased, and current requirements may call for more outdoor air than many buildings have the capacity to condition. Bringing the building up to code may require a significant investment in upgrades beyond those originally planned.

Making Retrofit Decisions

HVAC systems are major energy users, and new HVAC technology is far more efficient than 15 to 20-year-old systems in place in buildings. In some cases, the energy savings alone are so substantial that they justify the upgrade investment. But in many commercial office buildings it can be difficult to justify an HVAC upgrade. Perhaps some upgrades have been performed over the years, reducing the energy savings now available. Or perhaps the owner has a too short a payback-period requirement for energy upgrades.

When energy savings alone do not clearly justify an upgrade, how does the facility executive responsible for a commercial office building determine whether and how to upgrade the HVAC system? It is best to start with the building profile. A relatively small or mid-sized building (less than 200,000 square feet) may present marketing opportunities not available to larger facilities. For instance, instead of converting a constant-volume system to variable-air-volume (VAV), it might be possible to make each floor a separate zone. The marketing plan could then be changed to focus on larger, whole-floor users with large bullpen work areas that do not require multi-zone improvements.

In a medium or large-sized building, upgrade options will depend more on the type of system already in place. If the base building system is a constant volume system, with the main fans delivering varied air temperatures to large sectors of the building, there isn't much choice. To serve the varied needs of today's tenants, the facility executive will need, at a minimum, to increase the zoning abilities. How this is accomplished depends on the building's design and business plan.

For example, new speculative office buildings sometimes install heat pumps, which can deliver heating or cooling to small or large zones, are easily programmable, and operate at about 50 cents a ton per hour. But is the first cost for installing heat pumps a good value for retrofits? Probably not if the building was configured as a constant-volume or multi-zone system. Using heat pumps would require running condenser piping throughout the building and changing the fresh air distribution; what's more, the actual conversion could not run parallel to the old system if this retrofit was attempted in the summer because the cooling tower would be reused.

In this case, options for conversion should be limited to a VAV conversion or to individual zone diffusing that does not reduce energy costs but does create comfort zones similar to VAV systems. VAV systems provide a constant temperature to the space, but the air volume varies with the comfort setting. If the building was constructed after 1975, it probably has some type of VAV system installed. The earlier systems did provide easy zone creation; however, after-hour and flexible operation were usually not part of the operating system.

The most difficult VAV retrofit decisions are the ones where the payback related to energy reduction has already been captured by vortex dampers or by the later addition of variable frequency drives. If the facility will not receive an initial influx of energy savings, HVAC retrofits will have to be justified based on increased flexibility, after-hour operation and supplemental cooling. The facility executive must spend the time necessary to understand the overall value to the asset from a marketing standpoint.

It is important that all values are considered when making the decision. More is involved than just the cost of energy. There will be other gains that are not so obvious. A new cooling tower or new chiller not only operates with less kilowatts per ton, it also has new heat transfer surfaces, better part-load abilities and generally reduces maintenance requirements. The amount of labor and maintenance required to service a temperamental HVAC system can be quite a surprise once it is segregated from general operating costs.

The facility executive must also look at the useful life of the existing system. Will there be parts available next year? Is there a service company that will be willing to support the system? If a decision is made to sell the building will the system be flagged as unserviceable? Can the system still be used when a big block of space comes up in two years? These are all questions to ask when a system is facing obsolescence and when reliability of building systems becomes a factor in the marketplace.

There are other building details that sophisticated tenants are aware of or will become aware of if they enlist a good tenant representative or broker. Consider a broker with a client that is considering an existing building over the brand-new building across the street. The potential tenant is concerned with the condition of the HVAC system and requests the following information:

• Is the ductwork and distribution system clean? Please offer some verification.


• How is the insulation attached? Is it interior or exterior fiberglass?

• Is sound batting provided?

• What is the zoning per terminal?

• What are the temperature setpoints of the zones? How many zones are in my space?

• What is the noise level of the terminals?

• Can we control the perimeter zones of the offices separately?

• Is there any asbestos on the HVAC system, piping or ceiling?

• How can I operate after hours and what is the cost per hour?

• If I want to add some additional servers, is there a tenant tower for condenser water?


• What are the watts per square foot and the cubic feet per minute of ventilation air?

• What am I guaranteed in the future?

• How will I be billed for use of my after-hour heating and cooling?

In the last few years, tenants have been even more concerned with the office IAQ (Indoor air quality) environment. The more important the staff is to the operation, the more concern for the users' welfare. Tenants are asking more questions like these:

• What is the outside air ratio?

• Where does the outside air for my area originate and can you achieve 100 percent economizing?

• Do you have a proactive plan for indoor air quality complaints?

• Do you allow smoking?

• Do you have pressurization, smoke tower, stairway pressurization or smoke exhaust system?


• Are there any negative air situations in this building and does any of the air come from infiltration?

• Is there any redundancy to the heating and cooling systems?

• What is the origin, quality and reliability of the electrical service supplying the building HVAC system?

Competing for Tenants

Potential tenants may also want to see the property's preventive/predictive maintenance program, or to review the energy or computerized maintenance program to determine what occurs when the building operates outside its design parameters. This is when a facility executive must know the market. Can the property afford not to retrofit? Very often an energy payback exercise will show the project being way off the owner's target. But the analysis must also take into account lease-up value, tenant retention, cash flow and ultimately overall asset value. If a property is competing with a state-of-the-art VAV building with lower operating costs and greater flexibility, where are the tenants most likely to go?

In a landlord's market, a building with an outdated HVAC system may do all right. In a tight market, with a lot of available space, that property may either have to reduce rent, offer concessions or decide to give tenants what they really want: An HVAC system that is flexible, usable, efficient and able to provide comfort and good indoor air quality for employees.

Julian Arhire is a Manager with DtiCorp.com - DtiCorp.com carries more than 35,000 HVAC products, including industrial, commercial and residential parts and equipment from Honeywell, Johnson Contols, Robertshaw, Jandy, Grundfos, Armstrong and more.

Indoor Environmental Quality (IEQ) Problems And Opportunities

In reality, the perfect office doesn't exist today. Evidence that it doesn't, if any is needed, comes from a survey of members of the International Facilities Management Association (IFMA). IFMA asked more than 7,000 facility managers at U.S. corporations to rank the complaints they received most often. At the top of the list, according to the 2,400 respondents, were indoor environmental quality concerns. The biggest complaint was being too hot; number two was being too cold.

Employees responding to another survey reported difficulty doing their work because of poor indoor environmental quality. Those employees specified a number of factors as "stressors." Again, being too hot or too cold were among the top complaints. In fact, all of the top five stressors related to indoor environmental quality (IEQ):

1. Lack of air movement

2. Being too hot in summer

3. Stagnant air

4. Cigarette smoke

5. Being too cold in winter

IEQ is a broader term than IAQ - indoor air quality. IAQ deals specifically with the condition of the air within the building's occupied spaces. IEQ addresses the overall condition of the indoor space. Elements of IEQ include indoor temperature, ergonomics, noise and lighting, as well as the quality of the indoor air.

While there's no distinct line between IAQ and IEQ, what is clear is that the HVAC system has a substantial impact on both areas. What's also clear is that evaluating the HVAC system in light of the broader IEQ concerns can bring important benefits, including improved occupant comfort, reduced complaints and enhanced employee performance.

HVAC and IAQ

IAQ, of course, is a familiar topic for facility executives. It's also an area that's easy to overlook until a problem arises. Often, it is an accumulation of factors that cause the problem. Smoke, odors, dust and high occupancy in an area with too little ventilation all can decrease comfort and affect employee productivity. The U.S. Environmental Protection Agency (EPA) ranks indoor air as one of the top five environmental threats to human health. According to the World Health Organization, 30 percent of commercial buildings show signs of Sick Building Syndrome, including headaches, nausea, irritated nasal passages, itchy eyes and skin irritations.

Most code authorities recognize standards for ventilation air qualities established under ASHRAE Standard, which is based on the maximum possible number of occupants in the building. What complicates the matter is that, in the case of outside air, more is not necessarily better. The problem is how to avoid wasting energy by unnecessarily overventilating a building. Among the solutions are the methods used to control the ventilation, such as time-based ventilation, demand-based ventilation, carbon dioxide sensors and mixed gas sensors.

Controlling humidity

Humidity plays an important role in indoor environmental quality. If it gets too low, it causes respiratory problems, particularly for people with allergies, sinus problems or asthma. If it gets too high, more places become breeding grounds for microbial growth.

ASHRAE standards suggest relative humidity levels should be maintained between 30 percent and 60 percent. That means at times humidity needs to be added to the air and at other times it must be removed.

High relative humidity can have an impact on absenteeism and increases the potential for respiratory illnesses among workers. When relative humidity exceeds recommended levels, humans are adversely affected. Our sinuses are affected when humidity is too low and our skin dries out. Too high humidity causes different bacteria to propagate in mechanical systems.

There's another advantage to controlling humidity directly. The building owner can reduce energy bills in the heating season by reducing the temperature that would otherwise have been maintained and increasing the relative humidity within healthy ranges. The opposite can be done in the summer. Raising the temperature above what would otherwise have been maintained and lowering the humidity allows the body to evaporate moisture off the skin to stay cool.

While humidity and airborne contaminants are traditionally considered in IAQ analyses, other important IEQ factors may not be. Consider air movement. So many people look at IAQ from a system level and they tend to overlook what's happening in the occupied space. ASHRAE spells out rules for selecting a diffuser based on an air diffusion performance index (ADPI). An ADPI of 80 or higher assures adequate air movement.

Temperature is another issue that isn't always included in discussions of IAQ. One rationale for excluding temperature is that IAQ should be limited to health and safety issues.

Unfortunately, that distinction doesn't matter to building occupants who are complaining about their space. Rightly or wrongly, complaints about temperature are often attributed to poor indoor air quality. What's more, it can be difficult to separate health issues from ones tied to comfort.

Equally important is that employees who are uncomfortably hot or cold are likely to be less productive than they would otherwise be. That's one more reason facility executives are better off taking the IEQ approach to analyzing interior space.

Gains from good IEQ

A report for the National Energy Management Institute states that even in healthy buildings, a 1.5 percent productivity gain is possible when IEQ measures are instituted. In fact, the 1.5 percent gain is the conservative estimate; the report says that gains may be as high as 10 percent.

Productivity gains are not the only benefits from improving indoor environmental quality. Good IEQ also is good business.

To the building owner, good IEQ is a very clear plus. When you have good thermal comfort and good acoustic comfort, it differentiates your building from your competition. You can market your building as a clean and comfortable environment in which to work.

Analyzing IEQ

There are four basic steps to take. First, listen to your occupants and understand what they are saying about the building's indoor environmental quality. The second is walk through the building checking for those things and take specific measurements for those problems. The third step is to go back to the source - the HVAC system, for example - and take measurements there, making sure the equipment is doing what it is designed to do. The fourth step is to document any revised design or maintenance procedures that are taken to correct the problem. You also want to incorporate an occupant response mechanism for feedback to make sure you have corrected the problem.

Before making HVAC improvements, facilities executives need to conduct an economic analysis. Often, this analysis is based on utilities costs and savings. But, payback periods for HVAC improvements are much shorter when all major cost elements are added to the analysis. Such factors as building operating costs, salary costs and current productivity losses that could be regained shorten the payback period for proposed improvements.

Indoor environmental quality can be improved in nearly every building. And a number of steps can improve quality without costing much. In fact, many steps are just good facilities management.

You need to do proper maintenance of the building. Set up a checklist on a periodic basis and keep a log of all maintenance of your HVAC system. Do carbon monoxide monitoring for ventilation and make sure all controls are operating properly.

Facility managers and their staff need to fully understand how the HVAC and other systems in their buildings were intended to work and keep them operating in that manner. When major remodeling occurs or changes in space occupancy or usage, the ventilation and thermal requirements of the space need to be reviewed. When replacing equipment, the facility's staff needs to be involved in the selection, location and installation of the new equipment. This can help assure that the equipment will meet their needs and that they understand how it is to be operated and maintained. Building managers should also demand that the systems and equipment selected meet the currently established standards-of-care in that industry.

There are many solutions to indoor environmental quality problems, but it's not wise to wait for the crisis. Facility executives are better off looking now, before they have a problem. Chances are they'll find a number of IEQ issues that need to be addressed that can be handled at next to no cost. Half the issues that arise involve simple things your inhouse staff can do, like changing filters, cleaning drain pans, using high efficiency vacuums in housekeeping and so on. When you wait for the complaints, you are in a reactive mode trying to find a Band-Aid when you could have a more serious situation. If you consider IEQ now, you can take a more holistic approach and prevent your building from experiencing many IEQ problems.

Given all things on the facility agenda, it can be tough to find time to tackle a problem that no one is complaining about. But being proactive can pay off. One direct benefit is that, over the long term, a preventive approach will save time, perhaps a significant amount of time. There's another plus: Facility executives who can show senior managers that their actions have increased employee satisfaction or productivity are positioning themselves as problem-solvers and are demonstrating that the buildings they manage are assets, not costs.