Green Data Center Design and Build Strategies
- By Douglas Alger.
- Sample Chapter is provided courtesy of Cisco Press.
- Date: Aug 12, 2009.
- Siting the Data Center
- Building Design and Material Selection
- Data Center Configuration
- Strategies for a Greener Construction Site
- Building Commissioning
- Retrofitting an Existing Data Center
Chapter DescriptionThis chapter discusses methods for limiting the environmental impact that occurs during the construction of a Data Center through decisions concerning physical location, choice of building materials, landscaping choices and jobsite construction practices.
Building Design and Material Selection
Just as important as the decision of where to build your Data Center is choosing what to build it out of. Even if you've been involved in a lot of Data Center projects, this might be a new question (or series of questions) for you. Conventional Data Center Facilities are built with traditional construction materials—concrete, steel, lumber, drywall, glass, and copper, for instance. Employing different materials and streamlining their physical arrangement can result in a greener facility.
Avoiding the Landfill
One of the most straightforward strategies for making the design and build phase of your Data Center project green is to, whenever possible, avoid actions that cause anything to be thrown out.
That means employing high-quality, durable building materials. The fewer times you have to replace worn or damaged components, the fewer resources that are consumed. Also, choose materials composed of renewable resources, recycled content, or substances that would otherwise end up in a landfill.
Green options among common building materials include the following:
- Salvaged brick and stone: Using reclaimed brick and stone has become so popular in construction projects that businesses have emerged that are entirely devoted to collecting and providing such materials.
- Concrete containing fly ash: Fly ash is a fine residue created as a waste byproduct when coal is burned in electric power generation plants. Using the glass-like powder as a substitute for cement in concrete keeps it out of landfills and reduces demand for cement, the production of which generates significant carbon dioxide. Concrete containing fly ash is also stronger and easier to pump than that containing only conventional cement.
- Synthetic gypsum board or drywall: Like fly ash, synthetic gypsum is a waste byproduct of power plant coal combustion—in this case created when sulfur dioxide is removed from a power plant's exhaust flue gas. Such removal is required by law in many regions because sulfur dioxide contributes to acid rain. As with using fly ash in concrete, employing synthetic gypsum keeps this waste material out of landfills.
- Green insulation: All building insulation is inherently green because it improves energy efficiency. Cellulose insulation is considered even greener than conventional fiber glass insulation because it is made primarily from recycled newsprint. Another option is natural fiber insulation made from scrap denim, retrieved from clothing factories and otherwise bound for the trash.
- Sustainable wood: Wood is a renewable resource, assuming the forest it comes from is effectively managed to ensure its continued existence and replenishment. Several forest certification programs exist today that verify sustainability; the international Forest Stewardship Council is the best recognized. (FSC-certified wood is specifically referenced in the LEED rating system, for example.)
- Rubberized asphalt: Rubberized asphalt is a mix of regular asphalt and crumb rubber—ground up scrap tires. The material reduces tire noise and is less expensive than conventional asphalt; every lane-mile utilizes an estimated 2,000 old tires that would otherwise end up in landfills.
- Steel: Modern steel is made in one of two methods and, due to major cost savings of recycling steel over mining iron ore and processing new steel, both involve recycled content. Steel made through the electric arc furnace process in which an electric current is passed through scrap steel to melt and refine it, contains 25 percent to 35 percent recycled content. This type of steel can be flattened relatively easily and is used for items such as automotive body panels, exterior panels for major appliances and containers such as soup cans. Steel made through the basic oxygen furnace process, which combines molten iron from a blast furnace with pure oxygen, contains nearly 100 percent recycled content. Because of its great strength, this type of steel is typically used for items such as structural beams or plating.
Beyond employing individual recycled materials for your Data Center project, how about using a recycled building? That is, constructing your server environment within an existing structure rather than constructing entirely new. Even if you have to make major modifications for the pre-existing building to effectively house your servers, the project is still likely to consume fewer materials than a new build. Some of the environmental building assessment systems endorse this by awarding points for building reuse.
Embodied Energy and Emissions
You can take an even deeper look at how green your building's construction materials are by considering their embodied energy. That's the total quantity of energy expended in creating and providing a given item, including the following:
- Extracting raw materials
- Processing and manufacturing an item
- Transporting it
- Installing it
Broader definitions of the term embodied energy include the energy needed to maintain an item and ultimately recycle or dispose of it. A similar concept, embodied emissions or embodied carbon, refers to the carbon dioxide produced during those same stages of an item's life.
Accurately gauging the embodied energy and emissions of building materials can be extremely difficult. For one, no single method or formula has been agreed upon for calculating those values. Also, even the same building materials have their own circumstances unique to your specific project. How exactly was a given item manufactured? How far did it have to be transported, first to whatever outlet it was sold from and then to the construction site? For that matter, how was it transported? Different modes of transportation consume energy and produce carbon at different rates.
Despite such variables, several studies have been performed to classify embodied energy and emissions of various materials. Embodied energy is typically measured as a quantity of energy per weighted unit of building material, for example megajoules (MJ) per pound or kilogram. Embodied emissions are expressed as a quantity of carbon dioxide per weighted unit of building material, for example pounds or kilograms of carbon dioxide per pound or kilograms.
The University of Bath has compiled an Inventory of Carbon and Energy that includes embodied energy and carbon ratings for approximately 170 construction materials. Researchers drew information from a variety of published sources and, where regional elements needed to be incorporated, generally based them on factors relevant to the United Kingdom. (For instance, using the typical mix for electricity produced in the UK to help calculate embodied emissions values.)
Table 3-1 lists values for several common building materials, based on the University of Bath's Inventory of Carbon and Energy.
Table 3-1. Embodied Energy and Carbon of Common Building Materials
Asphalt (road and pavement)
Cement (25 percent fly ash)
Cement (50 percent fly ash)
0.43 to 1.5
0.94 to 3.3
Polyvinylchloride (PVC) pipe
A handful of lessons can be taken away regarding embodied energy and emissions:
- Buy local materials: The shorter distance that an item has to be transported, the lower its embodied energy and emissions.
- Buy materials with recycled content: Reusing an item or material invariably consumes fewer resources than using something new.
- Get back to nature: Goods made from natural components rather than man-made ones typically consume less energy and resources.
- Less is more: The fewer materials you use in construction, the less energy and carbon emissions that are involved.
Finally, as you consider embodied energy and emissions when choosing among various building materials, don't forget to compare items based on how they are actually used in the construction of a building. For instance, although steel has higher embodied energy and emissions than brick or stone, it also has greater strength relative to its mass. If you were to build a wall out of the three materials, you can obtain the same structural strength by using a smaller amount of steel—perhaps enough less to involve less embodied energy and emissions.
Maintaining Air Quality
The building materials and fixtures you choose for your facility additionally impact air quality, both outdoor and indoor, which in turn affects the health and productivity of employees. Because green considerations often focus upon the external environment, you might not automatically think of indoor air as a consideration for how green your facility is. Nearly all environmental building assessment systems include indoor air quality as a rating criterion, though.
Numerous building-related components—from paints and adhesives to flooring and carpeting to furniture and office equipment—contain contaminants. Some, such as ceiling tiles, produce particulate matter that can cause eye, nose, and throat irritation. Others include organic chemical compounds that evaporate into the air. Known as volatile organic compounds (VOC), these substances can emit smog-forming particles and make building occupants ill. VOCs typically include carbon-based molecules, although specific regulatory definitions about what substances are VOCs and what aren't differ by region.
According to the U.S. Environmental Protection Agency, health impacts from VOCs can include the following:
- Eye, nose, and throat irritation
- Headaches, loss of coordination, dizziness, and nausea
- Nosebleeds (epistaxis)
- Shortness of breath (dyspnea)
- Vomiting (emesis)
- Memory impairment
- Damage to liver, kidney, and central nervous system functions
- Cancer in humans and animals
As when dealing with any irritating or harmful substances, the severity of symptoms can vary based on concentration and length of exposure.
To maintain good air quality at your facility, choose paints, adhesives, sealants, wood products, carpeting, and other materials that are classified as low- or no-VOCs. Several countries mandate relevant products be labeled with their VOC content, and many manufacturers provide the information even in regions where they are not required to do so. If such information is not readily available for a product you are considering purchasing, inquire with the manufacturer.
During construction, provide ample ventilation when the materials are installed. Set up fans to expel polluted air outside during construction, not to bring outside air in. When possible, air out items before they are installed.
How many fans do you need to deploy to air out a building space? That depends upon three factors:
- The size of the area you're ventilating
- How frequently you want to fully replenish the area with fresh air, known as air changes per hour
- The air moving capability of your fans, which is typically listed in cubic feet per minute (cfm).
Various environmental and construction agencies recommend performing anywhere from 5 to 12 air changes per hour to maintain good air quality. To calculate the cumulative cfm fan rating you need to fully refresh the air in an area, take the size of the space in cubic feet, multiply it by the number of air changes per hour that you want, and then divide by 60.
For instance, if you have a room that is 15 feet by 15 feet wide, with a 10-foot ceiling, and you want to perform 5 air changes per hour, you need a fan rated at 187.5 cfm:
- 15 feet x 15 feet x 10 feet = 2250 cubic feet.
- 2,250 cubic feet x 5 air exchanges = 11,250 cubic feet per hour.
- 11,250 / 60 minutes = 187.5 cubic feet per minute.
(Using metric equivalents, that's a 63.7 cubic meter room; 63.7 cubic meters x 5 air exchanges = 318.5 cubic meters per hour. 382 / 60 minutes = 5.3 cubic meters per minute.)
As a more extreme example, say you want to air out your huge Data Center—a 100,000-square foot room with a 12-foot ceiling—at a rate of 12 air changes per hour. That room requires multiple fans with a cumulative rating of 240,000 cfm:
- 100,000 feet x 12 feet = 1,200,000 cubic feet.
- 1,200,000 x 12 air exchanges = 14,400,000 cubic feet per hour.
- 14,400,000 / 60 = 240,000 cubic feet per minute.
(Using metric equivalents, that's a 33,960-cubic meter room; 33,960 cubic meters x 12 air exchanges = 407,520 cubic meters per hour, and 407,520 / 60 = 6792 cubic meters per minute.)
Choosing Efficient Fixtures and Appliances
Although the vast majority of your building's resource consumption occurs in the Data Center, don't overlook other fixtures and appliances. Every watt of electricity you save, gallon (liter) of water you conserve, or pound (kilogram) of carbon dioxide that you avoid generating, the greener your facility is. It doesn't matter where in the building the savings occur.
This is especially true for mixed-use facilities, in which a notable portion of the building footprint is occupied by non-Data Center space. As mentioned in Chapter 2, it's often much easier to implement certain green practices in office spaces than hosting areas.
Efficiency opportunities can include the following:
- Lighting: Design office areas to maximize daylight, reducing the use of powered lights (and typically increasing the comfort and productivity of building occupants). Install timers and motion sensors so lights automatically shut off during times when employees are not present. Fluorescent T12 bulbs are the ubiquitous choice for ceiling lights, but thinner T8 and T5 bulbs use less energy—25 percent to 50 percent less by various estimates. (T indicates the tubular shape of the bulb; the number represents the diameter of the bulb in eighths of an inch.) Light emitting diode (LED) lights are used rarely in office buildings but can provide even greater energy savings.
- Office electronics: Choose energy-efficient office equipment. The U.S. Environmental Protection Agency's Energy Star program addresses computers, copiers, digital duplicators, fax machines, printers, and even water coolers. An excellent source of information about computers and monitors is the online Electronic Product Environmental Assessment Tool (EPEAT), which evaluates those devices according to 51 environmental criteria including material selection, packaging, energy efficiency, and to what degree a product's component parts can be reused or recycled at the end of its useful life. The tool is available at http://www.epeat.net.
- Power strips: In many workplaces, computer peripherals such as monitors, printers, and speakers are left on perpetually, even during nonbusiness hours. Several electrical power strips are on the market nowadays that detect when a primary device (that is, your computer) is either not present or not drawing power and then cut power to the other sockets that peripheral devices are plugged in to. This avoids desktop items drawing power when not needed, without having to rely on people to manually unplug them at the end of each workday.
- Kitchen appliances: Ideally your Data Center isn't located in a building that also contains a cafeteria or break room, due to the increased potential for a fire or water leak to occur. If it is, however, you can at least choose energy-efficient appliances.
- Plumbing fixtures: Even if your Data Center is located within a dedicated building that contains no office space or other regularly occupied areas, it will likely include one or more restrooms. Waterless urinals forgo the 1.5 gallons to 3.5 gallons (5.7 liters to 13.2 liters) of water per use of conventional toilets, typically saving tens of thousands of gallons (liters) per year. Auto-sensing sink fixtures can also reduce water, as do low flow shower heads if the building happens to include employee shower facilities.
Even fixtures that don't consume power or water can indirectly impact the building's energy efficiency. Designing work areas to be open or use low-height cubicle walls, for instance, improves illumination and can potentially reduce lighting needs.
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