Although carbon caps—mandatory limits on carbon dioxide emissions—have not yet become widespread, chances are they will be imposed upon business and industry in the near future, says Bob Vorwald, measurement and verification manager for Trane. Trane Inc. is a global provider of heating, ventilation, and air conditioning systems, as well as building management systems and controls.

“Green building is a developing trend,” says Vorwald. “Carbon caps are going to change the landscape and newer technologies—or even just taking better advantage of old technologies—are going to become more important.”

Start with Energy Analysis

Before considering renewable energy initiatives, owners of existing buildings should optimize energy usage. They often can save on energy costs without investing in additional equipment.

“Definitely start with an energy audit before you start looking at renewable options,” suggests Vorwald.

Preliminary audits are low or no cost; some can be done online at the Energy Star Web site (www.energystar.gov). These audits compare a facility’s energy usage to similar facilities in the same part of the country. Areas of a building where usage is already below average won’t benefit much from optimizing techniques.

A more detailed study, usually conducted by an engineering firm, runs about 10 cents per sf, notes Vorwald, and can cost upwards of $100,000 for high-performance buildings. A detailed analysis is necessary to determine the cost benefit and payback time. Other tools like software programs are available to analyze energy efficiency.

Fine Tune Existing Systems

For existing buildings, optimizing energy use often means paying closer attention to the machinery running HVAC and other large systems. This is especially true for buildings with energy management systems that control heating and cooling.

“There’s so much complexity to energy management systems. A key to energy savings is making sure these systems are used to their full potential,” says Vorwald.

Fine-tuning a building automation system can be done with minimal cost and result in a huge payback. The first thing to check: Does the automation run on specific time schedules, or operate HVAC systems 24 hours a day?

“Most building automation systems can be tweaked to the minute, or programmed for optimal start and stop control,” explains Vorwald. “The systems learn when they have to start in order to make the building comfortable by occupied time periods. It’s worth letting somebody spend time working on the energy management systems, whether you do it internally or hire outside help.”

New technology includes occupancy-based control sensors, which sense when people are in a room and adjust lighting and air systems accordingly. These are a good idea for sporadically occupied rooms, adds Vorwald.

Another item that should be addressed early on is lighting. Older lighting produces more heat, so by retrofitting lights first, building owners can save money on cooling.

“Retrofitting the lighting systems first can actually help to reduce the size of the cooling plant,” says Vorwald. “Cut energy use first, because that’s where the fastest payback is going to be. Then look at something like solar panels to reduce usage even more.”

Begin and End with Green Technologies

Adding energy efficient technologies to new buildings is easier than upgrading existing facilities, although they usually entail more upfront costs.

“It might cost you a little bit more in the beginning for certain approaches, but you have to consider whether it’s cheaper to spend it up front or to retrofit later on,” says Vorwald.

The three major green technologies that can benefit high-performance buildings are chillers, building automation systems, and renewable energy.

Chillers are at the heart of the air conditioning systems. A centralized refrigeration process chills (in most cases) water. The water is then pumped around the building and travels through coils, where air blows over the cold water and cools the air. Water returns to the chiller to be cooled again.

“It’s a real efficient way of cooling a large facility,” notes Vorwald.

Chillers can be used in a variety of capacities, but are common in a dense environment where buildings are close together. Large commercial chillers can reduce energy consumption by half.

At the Hillsborough County Government Center in downtown Tampa, Fla., eight buildings share a chiller system. While building a new courthouse, the county saw an opportunity to centralize chilled water production. An energy efficient central plant was built in 2001, then expanded with a thermal storage system. The actual savings for this project have amounted to more then $1.2 million in the first two years.

The Providence Newberg Medical Center (PNMC) in Newberg, Ore., created a green facility when constructing a new hospital in 2002. Two centralized chillers control the fully integrated HVAC systems. The effort earned PNMC the U.S. Green Building Council’s first Leadership in Energy Efficient Design (LEED) Gold Certification for a hospital on the West Coast.

Building Automation Provides Cost Saving Possibilities

Current building systems include energy recovery, geothermal heat pumps, thermal storage, and ventilation optimization. All provide a degree of energy cost savings.

Energy recovery systems using chillers help high-performance buildings use less energy to cool fresh air brought into the building in summer and to pre-heat cold fresh air from outside in winter.

In the case of Children’s Hospital Los Angeles, an advanced hybrid HVAC system combines steam absorption and electric centrifugal chillers. The new system takes advantage of an abundance of steam, allowing the hospital to operate the absorption chillers very efficiently.

Thermal storage enables building owners to take advantage of lower nighttime utility rates. Chillers run at night, and build ice that in turn chills tanks of water for later usage. These systems often use more total energy, but there’s a large savings on dollars, says Vorwald. Thermal storage can require a lot of space, depending upon the number of storage tanks needed. The systems use the chemical glycol for freezing, which, because it is a toxic substance, may be an issue for building owners and operators.

When Morgan Stanley’s 23-story building in Westchester, N.Y., generated high energy costs, aging equipment was the culprit. The building needed additional cooling capacity. The solution is a 1400-ton chiller operating at .576 kilowatts per ton in day mode and .733 kilowatts per ton in ice-making mode. The facility reduced fuel consumption by 15,000 MMBtu, received a $300,000 incentive from the state, and generated reductions in carbon emissions equal to planting 1.5 million acres of trees.

Geothermal heat pumps take advantage of the year-round stability of ground temperature to heat and cool buildings. The West Philadelphia Enterprise Center in Pennsylvania uses a geothermal heat pump system for more than 31,000 sf of space. The energy efficiency of the system is high, with unit coefficient of performance approaching 4.0. The indoor air quality also is excellent.

Ventilation control is another energy-saving option to consider, says Vorwald. By law, building owners must provide a minimum amount of ventilation for people in occupied spaces, so HVAC costs are huge. However, there are a variety of ways to pare those costs.

Carbon dioxide sensors the size of thermostats can be placed in rooms or the return air stream. Sensors reset the amount of ventilation based on carbon dioxide levels. Making sure air dampers are set properly can aid energy efficiency as well, as can the aforementioned occupancy sensors. Supply air reset helps building systems adapt to the outside air temperature, and fan pressure optimization controls static for better efficiency.

Renewable Energy: a Growing Resource

On-site renewable energy, by the U.S. Green Building Council’s definition, includes photovoltaic systems, cogeneration, wind, biofuel-based electrical systems, geothermal heating systems, geothermal electric systems (using the Earth’s steam to make electricity), and low-impact hydroelectric power systems.

Since the Sun’s rays were first transformed into electricity with photovoltaics in the 1970s, the price has dropped substantially—from about one dollar per kilowatt hour to less than 10 cents per kilowatt hour, depending on the application. They still require a large upfront investment, and efficiency averages about 10 percent, although the science is quickly improving. Photovoltaics are helpful in shaving peak power usage, since the highest demand usually occurs when the sun is at its hottest.

“You can reduce the demand on the building and pay less to your utility company. However, it may not be practical to design a photovoltaic system to handle 100 percent of your load,” advises Vorwald.

Co-generation uses one fuel (gas, oil, or diesel) to produce two outputs—electricity and heat. The advantages, besides lower utility costs, include more self-sufficiency. ConEd in New York City is one of the largest users of co-generation, producing 30 billion pounds of steam each year through seven plants at 360 MW before pumping it to 100,000 buildings.

Geothermal electricity generation releases only one to three percent of the carbon dioxide emissions of a fossil fuel plant. At the Fort Knox, Ky., U.S. Army base, the world’s largest geothermal heating and cooling system has contributed to an annual energy savings of $3.5 million and has cut emissions by one-third.

Wind power generates large amounts of electricity at low cost and with zero emissions, but largely because of zoning and placement issues currently produces only about one percent of worldwide electricity.

Reliability Centered Maintenance

There are plenty of tools available for monitoring and improving the efficiency of high-performance systems. Reliability centered maintenance helps building owners predict maintenance needs, rather than simply do preventive maintenance, which can cause problems with sensitive machinery.

“With ongoing monitoring you can analyze when a device may need maintenance or need replacement,” says Vorwald.

Monitoring tools include thermal imagers and infrared thermography to detect heat, vibration analysis machines, lasers that check alignment, and various ultrasonic devices that detect leaks and lubrication issues.

Predictive maintenance requires specialized equipment and must be done more frequently, so measure the cost of the predictive maintenance requirements against what a system breakdown would mean to your business, advises Vorwald.

The Bottom Line

The bottom line, says Vorwald, is that green building is here to stay. Building owners, tenants, customers, and employees want it. Investors, governments, and businesses are beginning to demand it.

Not only is green building good for the environment and future generations, but it’s also good for business and investment, and the power grid. Green is do-able because the technologies exist, the tools are in operation, and planners and builders now have the knowledge to make it work.

By Taitia Shelow

We welcome your Questions and Comments

Copyright 2008 Tradeline Inc.
All Rights Reserved
ISSN: 1096-4894