Is Your Building Conducive to the Installation of a Green Roof?

Any reason for installing green roofs on a building—whether it’s to save money or the environment—is a good reason.

By Richard Heller and Chris Psencik
View the original article here
February 4, 2014


According to the Green Roofs for Healthy Cities (GRHC) association, the North American green roof industry grew by a remarkable 24 percent in 2012. Part of this growth was spurred on by more cities recognizing the public benefits of green roofs and taking various policy measures to encourage their widespread installation. However, according to GRHC there is still enormous potential for growth of new green roofs on billions of square feet of buildings across North America.

Despite the potential, installing a green roof is not a decision to be taken lightly. There are several structural and site/location considerations to take into account. The most recent news of a probable green roof collapse at a Latvian supermarket should give one pause. Before allocating the time and resources, facility owners and managers should weigh the pros and cons of a green roof and what to keep in mind during the planning stages.

The Mental Checklist

First, you need to consider the load capabilities of the building. The space that is designated for the green roof: Is it able to sustain the weight for the items that will be designed and placed on top of the roof? If the live weight load (after snow, for example) is less than 35 pounds per square foot, it will be harder to establish a green roof.

Second, consider the design intent of the green roof. Is the space going to be an area that individuals will be able to visit and enjoy up close, or is the green roof only to be viewed from a window, door, patio, etc?

Third, take into account the location and climate of the intended green roof. A common misconception about green roofs is that they must always be green and vegetative, but there are several possibilities. However, one needs to consider the climate and the exposure. For example, the west side of a building is going to have a tremendous amount of sun and heat, so plant materials will need to be suited to sustain themselves in this environment. The north side will receive colder northern winds and can be more heavily impacted by freezing temperatures.

In many instances the natural environment is not the only factor to consider when designing a green roof environment. Microclimates will also be created from the structure surrounding the space. For instance, radiant heat will increase exponentially when planting next to mirrored glass. Overhangs will create opportunities for shade gardens. Planting soil depths and soil material makeup will determine how quickly or slowly a space will dry out in rainy or dry seasons.

Fourth, consider irrigation and drainage. Drainage is key in making sure that rooftop gardens do not become pools. Rock gardens are commonly used in situations where irrigation cannot be provided and temperatures are determined to be too extreme in a green roof environment. Draining and irrigation issues can be solved with construction, but this will add costs to any budget.

Finally, one must ask if a green roof is the best choice for achieving goals. Many of the functions of a green roof can be achieved through other means. For example, rainwater from roofs can be recycled for irrigation. Heat can be mitigated by shade trees, which are the backbone of the ecology and support far more beneficial insects than most green roofs ever will.

In an urban environment, where there is almost no ecology and nature has been paved over, green roofs can play a vital role. In a suburban environment, however, the functionality of green roofs may become harder to justify when one looks at other alternatives.

Green Roofs Expand Green Spaces

According to the Environmental Health Research Foundation, each day a 50-foot by 50-foot green space releases enough oxygen to support a family of four, and the Center for Disease Control and Prevention (CDC) points to the positive mental health benefits of being exposed to parks and green spaces.

Green roofs offer various opportunities for owners and employees to experience a little bit of nature. For example, the Fairmont Hotel in downtown Dallas developed a vegetable garden green roof, which allows the kitchen to provide fresh, locally grown herbs, spices and seasonal vegetables that go straight from the garden to the plate.


At the University of North Texas (UNT) Business Leadership building, a series of outdoor green roof spaces created by Southern Botanical and Lindsey White of Caye Cook and Associates allows students and faculty an opportunity to leave the classroom and office to take a break to reflect and study.

These spaces also help with the conservation of energy for the facility by increasing natural lighting within interior rooms and corridors. In turn, the increased natural light offers an opportunity to save on energy and lighting costs for the facility.

But there are also some concrete reasons for installing a green roof.

Green roofs can protect the roof membrane from elements that can be destructive, such as extreme heat and cold, water, mechanical damage and ultraviolet rays. In some cases, a green roof can double or triple the life of the membrane when properly installed and maintained.

Additionally, there are energy savings since a green roof acts as an insulator. Green roofs can also mitigate the heat island effect, reduce rainwater runoff, and to some extent, replace the flora that was destroyed by the footprint of the building.

For many cities, a compelling reason for green roofs is to offset the underlying, weak urban infrastructure that is overwhelmed by rainwater runoff.

New York City, for example, has an antiquated sewage system which, when overwhelmed by rainwater, forces the city to dump raw sewage into local bodies of water and makes New York beaches unusable for several days thereafter. In this instance, green roofs absorb 80 percent of the water that lands on them, so they can be a strategy to reduce the amount of water that reaches urban infrastructures.

Expecting Positive Growth for Green Roofs

The USGBC and its LEED certification program are spurring on the design and installation of green roofs all over the country. There are some regional variations, but that is often tied to climate. In Texas, for example, extreme temperatures can be somewhat of a limiting factor.

The increase in green roofs is often a matter of education, cost and technology, but signs indicate that they will become more productive and/or habitat-oriented. Green roofs will become popular as a site for food production, a habitat for beneficial insects, a way station for migratory birds and so on. This is a trend that is already happening in some cities and will continue to expand as food prices rise, and natural habitats continue to be reduced by population pressure.

And green roofs will continue to grow as a market segment as they establish track records and are supported by legislation.

For example, New York City gives a tax rebate for green roofs more than a certain square footage because the city recognizes that every square foot of green roof means less money it will have to spend upgrading the sewer and rainwater infrastructure.

In the end, consider function first and make sure your building and location are amenable to a green roof, or be clear on the extent of changes that need to be made and costs that need to be incurred for it to function properly and safely. Then be clear on the “why.” If the “why” is that you want to reap the qualitative benefits for employees and the environment, that is okay, too.

10 Smart Building Myths Busted

May 6, 2014 by Lee O’Loughlin

View the original article here

Smart buildings are a no-brainer and more affordable than most building owners and investors realize.

Smart buildings have been proven to save energy, streamline facilities management and prevent expensive equipment failures. Yet, to many property owners and investors, the value of smart buildings remains a mystery. The fact is, in most buildings, we can demonstrate a strong business case for strategic investments in smart building systems and management technologies.

Not everyone is aware that the tremendous advantages of today’s affordable smart building management technologies easily justify the cost. The following are 10 myths about smart buildings, along with the facts:

Myth #10: Smart Building Technologies Are Expensive.

Myth Debunked: Smart building technology investments typically pay for themselves within one or two years by delivering energy savings and other operational efficiencies. One smart building management pilot program we worked on, for example, generated a positive return on investment within several months.

Myth #9: Smart Buildings are Only About Energy.

Myth Debunked: A smart building management system often can detect when a piece of equipment is close to failure and alert facilities personnel to fix the problem. Knowing the right time to repair or replace equipment extends machinery life, and reduces facility staff, operations and replacement costs. More dramatically, smart building management systems can prevent full-scale building system failures—potentially embarrassing to a Superbowl stadium host, but life-threatening in a hospital or laboratory.

Myth #8: Smart Buildings and Green Buildings are the Same Thing. Myth Debunked: Smart buildings maximize energy efficiency from building systems and ensure air quality, while a complete “green” sustainability program includes strategies beyond building automation systems. So, while “smart” and “green” features may overlap, they are not identical concepts. The Continental Automated Buildings Association (CABA) explains the difference in Bright Green Buildings: Convergence of Green and Intelligent Buildings, a comprehensive report authored with Frost and Sullivan.

Myth #7: Industrial Facilities or Laboratories Can’t Become Smart Buildings.

Myth Debunked:  All types of buildings—whether residential or commercial—can be built or retrofitted to become highly automated and smart. Even highly specialized facilities such as laboratories can be outfitted with smart building technologies.

Myth #6: Smart Buildings Can Only Be New Buildings.

Myth Debunked: Some of the smartest buildings in the world are not new at all, but have demonstrated the return on investment in smart technologies. The Empire State Building, for example, has exceeded projected energy savings for the second consecutive year following an extensive phased retrofit begun in 2009.

Myth #5: Smart Building Technologies are Not Interoperable.

Myth Debunked: In the past, building automation equipment and controls were designed as proprietary systems. However, affordable new technologies, such as wireless sensors, now make it possible to gather data from disparate systems produced by any manufacturer.

Myth #4: Smart Systems Don’t Make a Building More Attractive to Tenants.

Myth Debunked:  Anything that improves energy efficiency, reduces occupancy cost and improves productivity is valuable to tenants, as numerous studies and surveys attest. Tenants and their advisors increasingly expect smart building features such as zoned HVAC, sophisticated equipment maintenance alert systems, and advanced security systems. As reported in JLL’s October 2012 Global Sustainability Perspective, smart systems provide benefits for tenants—and tenants recognize the benefits.

Myth #3: Without a Municipal Smart Grid, a Building Can’t Really Be Smart.

Myth Debunked:  It’s true that smart buildings gain functionality when supported by advanced electrical grids installed by municipalities and their utility company partners. But even without a smart grid, owners and investors can draw a wide range of benefits from smart buildings and a smart building management system that can monitor entire property portfolios.

Myth #2: Smart Buildings Are Complicated to Operate.

Myth Debunked: Combined with a smart building management system, a smart building is often easier to operate and maintain than a building that lacks automated systems. A smart building management system can integrate work-order management applications; pull equipment repair and maintenance data into performance analytics; and pinpoint equipment issues to a degree not humanly possible. For example, a smart building management system can diagnose a programming problem that has been undetected for 15 years, enabling facility managers to resolve a recurring equipment malfunction.

Myth #1: Smart Buildings Are a No-Brainer.

Myth NOT Debunked: This myth isn’t a myth at all — it’s actually true. As affordable new technologies are adopted, tenants are beginning to expect smart building features—and owners and investors are beginning to realize the return on investment in smart systems.

Leo O’Loughlin is senior vice president of Energy and Sustainability Services at JLL, the global professional services and investment management firm offering specialized services to clients that own, occupy and invest in commercial real estate. With 20 years of energy and sustainability management expertise, Leo helps clients incorporate energy and sustainability concepts into operations and project management, reducing energy consumption, utility expense and carbon emissions. He specializes in creating and analyzing project structures for energy efficiency, central utility plant and energy services outsourcing programs, managing the multi-disciplinary development of energy infrastructure assets and retrofit projects. He also manages business development, commercial structuring, financial and technical analyses and implementation of energy-related projects. Previously, Leo was an executive at several leading California energy companies. He holds an MBA from San Diego State University and a BS in mechanical engineering from Purdue University.

‘Green’ Federal Facilities Save $42M

Environmental Leader, 05/27/2014

More than 400 federal facilities achieved $42 million in cost savings and environmental benefits last year as part of the Federal Green Challenge (FGC).

A national effort under the EPA’s Sustainable Materials Management Program, the FGC allows federal offices or facilities to pledge participation in reducing the federal government’s environmental impact and recognizes outstanding efforts that go beyond regulatory compliance and strive for annual improvements in selected target areas (waste, electronics, purchasing, water, energy and/or transportation).

Within these areas, additional accomplishments by participants included: diverting more than 500,000 tons of municipal solid waste and construction and demolition waste from landfills, and reducing fleet distance traveled by 16.5 million miles.

Data collected from the challenge show that FGC participants sent 1,765 tons of end-of-life electronics to third-party certified recyclers, minimizing environmental impacts — including water and energy use, releases to air and water, greenhouse gas emissions, and land use impacts.

The US General Services Administration’s new standards for its federal buildings, published in March, focuses more on outcomes, or performance, and less on technology.

The Facilities Standards for the Public Buildings Service, also known as the P100, is a mandatory standard that outlines how facilities will be managed, designed and built to achieve higher performance levels and save energy in the 9,200 buildings the GSA owns and leases across the country. The P100 applies to all new construction projects including additions to existing facilities.

Right-Size Your Ventilation Needs

Learn how demand control ventilation can reduce energy use

By Jennie Morton
View the original article here

Can ventilation requirements and energy conservation go hand in hand? They can if you implement demand control ventilation (DCV).

There’s no reason to waste energy conditioning air for people who aren’t in your building. Instead of supplying air at fixed rates, DCV automatically adjusts ventilation levels based on real-time occupancy measurements. This strategy allows you to meet code and reduce energy use without sacrificing indoor air quality.

The problem with traditional ventilation is that it cannot distinguish between actual vs. projected occupancy. As outlined in ASHRAE 62.1-2013, Ventilation for Acceptable Indoor Air Quality, ventilation rates are calculated using two factors: square footage and peak occupancy.

Since square footage is a constant, any fluctuations on the occupancy side of the equation give rise to energy waste. With travel, sick days, vacation, and inclement weather, your building is rarely at capacity. In fact, human resources data shows an average of 75% of workers will be in attendance at any given time.

Without a way to calculate the actual headcount, your HVAC system operates as if maximum occupancy occurs on a continuous basis. If you can eliminate the excess air supply whenever fewer people are present, however, you have an opportunity to capture energy savings.

To have a responsive, intelligent HVAC system, you need to implement demand control ventilation. This strategy recognizes when a space has fewer people than scheduled and drops ventilation levels accordingly, explains Daniel Nall, senior vice president with Thornton Tomasetti, an engineering firm. Air supply is calculated using verified headcounts rather than occupancy projections. DCV is no different than using occupancy sensors to control lights – both ensure energy is conserved when there’s no activity in a space that justifies its use.

For example, offices need to supply 5 cubic feet per minute (cfm) per person in addition to a baseline of 0.06 cfm per square foot, Nall explains. Unoccupied, a 250-square-foot office needs 15 cfm to meet the ASHRAE standard. With one individual present, this increases to 20 cfm. Using DCV to sense when the room is empty, you can scale back the ventilation from 20 to 15 cfm, a 25% decrease in air supply. These savings are then multiplied across any room that has DCV capability.

If your occupancy variations are known in advance, DCV may be as simple as using a basic schedule in a building management system, says Jules C. Nohra, manager for energy efficiency at SourceOne, an energy consulting and management firm. Those with irregular or unforeseen occupancy fluctuations, however, will require sensors that can determine how many people are present. These include education, retail, conference areas, performance venues, lobbies, and offices with a mobile workforce or flex hours.

Carbon dioxide monitoring is by far the most common way to determine occupancy, says Thomas Lawrence, senior public service associate with the College of Engineering at the University of Georgia. The technology is well-established and straightforward to implement. CO2 isn’t treated as a contaminant that needs to have its levels controlled (a common misconception), but as a representation for the number of bodies in a space.

“Carbon dioxide measurements act as a surrogate for occupancy because humans generate an average volume per hour,” explains Nall. “By calculating the concentration differential between internal CO2 volumes and the outside air, you can estimate the number of people in your building. For example, if your CO2 concentration doubles, then occupancy has doubled.”

Occupancy sensors, such as the infrared ones you pair with lighting controls, can also be used. These are the most effective in individual work spaces and private offices, Lawrence observes. For a zone with multiple workers, however, they don’t offer fine enough measurements to calculate total attendance.

For example, think of an open floor plan that houses 30 people. The occupancy sensor will trip when the first person arrives, but it can’t scan the room an hour later to see if all 30 workers showed up that day. It also can’t detect if 15 of those employees move to another part of the building for a two-hour meeting, leaving the space over-ventilated during that period.

Entertainment venues may be able to use ticket sales to confirm a headcount. Other facilities can derive occupancy by counting cell phone signals present in the facility, Lawrence says. It’s also possible to have IT report the number of active computers, assuming that each device fired up represents a person in the space. If you use an access control system and it can interface with your BAS, each card swipe, keypad entry, or turnstile rotation can count toward occupancy.

Integrating demand control ventilation is heavily influenced by your existing HVAC system, such as whether your ventilation is combined with heating and cooling or is a standalone function.

“For example, adding DCV to a packaged rooftop unit may be as simple as including the CO2 sensor with a controller that has the DCV control logic built into it. Such a system likely serves only one or a few occupied zones, making it simpler to control CO2 levels,” explains Lawrence. “A larger building with central air handling, however, may serve many occupied zones. Determining the proper amount of outdoor air to bring in at the central air handling unit is also complicated by the variable occupancy patterns within the multiple zones.”

Say your VAV system supplies air to a large conference area and a group of private offices. To scale back the ventilation when the conference room is empty means that you risk the possibility of underventilating the offices at the same time. To avoid this scenario, you will need air flow sensors that measure the amount of air going to each space as well as the outside air that’s being drawn through the air handling unit, says Nall.

CO2 sensors are typically installed in the occupied space instead of ductwork because return air is an average of all conditioned spaces rather than an individual area, state ASHRAE members Mike Schell and Dan Inthout in their article Demand Control Ventilation Using CO2. Duct sensors can be used if all ventilated spaces share common occupancy patterns; otherwise, sensors should be wall-mounted.

“Avoid installing in areas near doors, air intakes or exhausts, or open windows,” advise Schell and Inthout. “Because people breathing on the sensor can affect the reading, find a location where it is unlikely that people will be standing in close proximity (2 feet) to the sensor. One sensor should be placed in each zone where occupancy is expected to vary. Sensors can be designed to operate with VAV-based zones or to control larger areas up to 5,000 square feet.”

Switching to DCV will typically require additional building management system points, new setpoints, and new control codes for dampers, Nohra notes. This may include a controller or DDC programming to communicate either directly with the economizer controller or a central control system, specifies the DOE in its 2012 report on demand control ventilation.
You should also make sure outdoor dampers are operable and not stuck in fixed positions, stresses Lawrence. It’s not unusual to find air intakes blocked in a misguided attempt to save energy. There may also be missing equipment, such as economizer controls with modulating air dampers that were specified but never installed.

Once the DCV sequencing has been established, the system requires minimal maintenance. CO2 sensors should be recalibrated periodically as their accuracy will drift over time. Consult your manufacturer guidelines, which may recommend recalibration every five years, annually, or every six months. Lawrence also recommends sensor testing prior to launch in case the product is deficient or was damaged during installation.

Demand control ventilation isn’t a flashy energy efficiency project, but it consistently generates payback under five years or less. Paybacks can also be achieved more quickly if the system incorporates lighting and electrical outlets (vampire energy) controls. For upfront investments, owners can expect to pay less than $100 for occupancy sensors, Nall estimates. CO2 sensors can cost several hundred dollars per unit, adds Lawrence.

“The installation costs for a DCV project vary significantly depending on building size, existing infrastructure, and control requirements. An owner can expect to pay approximately $1,000 to $2,000 per point on average,” Nohra adds.
Nall was recently involved with a renovation project that incorporated DCV by using occupancy sensors. A series of perimeter offices and those adjacent to an atrium were paired with a dedicated outside air system and variable speed fan coils.

Each 160-square-foot office has a two-position damper. The default setting for an unoccupied office delivers 10 cfm of outside air. Anticipating occupant diversity when the office is in use, the secondary position is configured for three guests at 25 cfm.

“This ensures that we’re providing the minimum ventilation for the maximum expected occupancy,” Nall stresses.
Whenever the system senses the room is unoccupied, it can scale back ventilation to 40% of peak flow. The project cost less than $1,000 per office and since the occupancy sensor controls ambient lighting and power receptacles, the payback is under five years. The DCV capability also meets the LEED credit for increasing ventilation by 30%.

Lawrence also oversaw a DCV project at the University of Georgia. The retrofit converted a single classroom, but has seen great success since its installation. Payback was achieved in less than two years and there are plans to adapt more areas in the future.

“Regardless of the actual design standard, energy savings with a DCV retrofit should focus on a comparison to the existing ventilation patterns, even if they do not match current codes or standards,” emphasizes Lawrence. “If a building is not providing ventilation that meets existing standards, then the primary benefits of DCV are indoor air quality.”

Jennie Morton jennie.morton@buildings.com is senior editor of BUILDINGS.