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EXPANSION JOINTS
During severe weather or seismic events, buildings are often subjected to loads that cause them to move in various ways. This movement is planned for in normal circumstances using building expansion joints. Since those joints are often vulnerable to the impacts of severe events, it is important they are properly addressed as part of a resilient design. Otherwise, the building itself can be directly impacted since the joints are meant to be the “relief valves” for forces allowing the building to appropriately move, absorb, or otherwise react and remain safe to use.
There are three fundamental types of forces that can act on buildings where expansion joints are needed. These include thermal expansion and contraction, seismic activity, and wind loads. Each of these are discussed further in the following sections with a focus on avoiding or minimizing damage to the building and/or harm to people.
Thermal Movement
Thermal movement in buildings is caused by daily environmental temperature changes in and around the structure. Thermal movement is primarily “one-directional” in nature and is the result of the expansion and contraction of a building as it is affected by heat, cold, and humidity levels. The amount of movement thermal joints must accommodate is defined by a structural engineer throughout the building but typically has a movement of plus or minus 10-25 percent of the nominal joint size. This aspect of resilience shouldn’t be ignored since it’s been noted that if a proper expansion joint isn’t present, there’s a good chance that Mother Nature will put one in for you – just not in ways that we are happy with.
Climate directly impacts thermal movement, so different locations will likely experience different amounts of thermal movement. A building near the equator with fairly constant year-round weather will likely experience much less variability in temperatures and humidity than, say, a building in New York City or Northern Germany. For example, if we look at a place like Ponce, Puerto Rico, which is near the equator, the temperature moves only a few degrees above or below the average of 77°F (25°C). By contrast, New York City has a 10-year average temperature swing from a low of 27°F (-3°C) to a high of 86°F (30°C) – almost 60 degrees F in difference on average. Of course, there can be days where these averages are exceeded, meaning that the total temperature swing can be well over 60 degrees throughout the year.
The significance of bigger temperature swings is that expansion joints need more area to move – the bigger the temperature swings, the bigger the need for the building to expand or contract accordingly. With average temperatures changing in many locations, that means that more expansion and contraction capacity may be needed, particularly in areas that are receiving new episodes of extended periods of extreme heat. A classic example of this type of problem is evidenced in pavement buckling in summer – the combination of ambient high heat and solar load causes the pavement to expand, and at weak points it buckles or literally “explodes.” Buildings may not experience as violent an event, but if expansion joints aren’t properly sized, designed, and installed, thermal expansion and contraction can cause buckling of surfaces such as roofs and interior floors. That can open the building to the elements and cause more weather-related damage.
The larger the structure (such as stadiums and airports) the more area that is exposed and vulnerable to thermal effects. This was a concern for architects and engineers designing a terminal expansion at the Manchester Airport in the United Kingdom. The $1.36 billion expansion of Terminal 2 made it 150 percent larger than the original to boost passenger capacity and provide gate and tarmac space for the largest jets now in operation. The new terminal also features 32 new shops and food and beverage outlets.
Architects were concerned about thermal movement creating a 7⁄8-inch (20mm) difference in floor heights across the slabs or sections of the terminal. This much difference would present a significant trip hazard for pedestrians transiting the terminal. Even worse, it could potentially be present for weeks or even months during the hottest or coldest times of the year. The solution selected by the design team was to create a project-specific “glide plate” floor joint. This custom solution had to move in three directions while simultaneously addressing the rigorous heavy-duty loads encountered in this major transportation hub. By properly accounting for all this movement, the expansion joint system was able to prevent both damage to the building and harm to people.
Photo courtesy of Inpro; Source: Prairie State Wire
Hot pavement surfaces that are not protected with proper expansion joints can buckle and “explode,” as shown on the left. Buildings with properly installed control joints, as shown on the right, help prevent such damage.
Seismic Movement Section
Seismic activity is caused by shifting of the earth’s tectonic plates causing earthquakes, tremors, etc., along fault lines. Among the complicating factors for resilient building design, seismic movement may be horizontal, vertical, in shear, or a combination of all three. That means seismic expansion joints need to be able to accommodate all these different movements. For taller buildings, the higher floors may actually move more than the lower levels as the building is caused to sway from its base. All of this means that seismic expansion joints must have the capacity for movement associated with them of plus or minus 50-100 percent.
In the United States, California and the San Andreas Fault are often thought of as the prime location for seismic activity. In reality, there are numerous seismic zones all across the country that require seismic design attention. The reasons for that activity can vary based on location, but it remains a genuine concern and resiliency threat.
It’s important to recognize that minor earthquakes are far more prevalent than severe or very large quakes such as the magnitude 6.7 Northridge quake in California in 1994 or the 9.1 magnitude earthquake (and tsunami) off Sumatra in 2004. Instead, most earthquakes are well below these levels but strong enough to cause temporary or permanent damage. Therefore, seismic expansion joint systems are best selected as products that can “reset” themselves after a minor seismic event and allow cover panels to be repositioned easily.
Note, too, that some geographic locations have seen an increase in seismic activity that has been linked to oil and gas exploration and production. Hydraulic fracturing (or fracking) may be causing pocket collapses and slippage between layers of rock that trigger small seismic events. In other cases, it appears to be something different. For example, the U.S. Geological Survey reports that beginning in 2009, Oklahoma experienced a surge in seismic activity. This surge was so large that its rate of magnitude 3 and greater earthquakes exceeded the rate in California from 2014 through 2017. While these earthquakes have been induced by oil and gas related processes, few of these earthquakes were induced by fracking. Rather, most earthquakes in Oklahoma were determined to be caused by the industrial practice known as "wastewater disposal". This is a process in which fluid waste from oil and gas production is injected deep underground far below ground water or drinking water aquifers. In Oklahoma over 90 percent of the wastewater that is injected is a byproduct of oil extraction process and not waste frack fluid.
Images courtesy of Inpro; Source: U.S. Geological Survey
The areas of the United States affected by seismic activity, and the risk of damage to buildings, are documented and available through the U.S. Geological Survey.
Design and construction professionals have regular reminders that buildings can suffer serious damage or even be destroyed by weather and location-related events such as severe storms, intense heat, attacks, or earthquakes. Media and professional journals regularly describe the impacts of these events, but more significantly, an increasing number of design professionals experience them directly – either from personal experience or through project work. Many building owners, too, have experienced the impacts or the liability concerns associated with such events and the need to recover quickly from them to maintain operations. This growing awareness of the potential hazards and risks to both people and property has prompted the development of codes and standards upon which to base design decisions. This course focuses on some specific strategies that can be used to address the concerns of serious events, whether natural disasters or human-made. In particular, aspects of design are addressed related to withstanding such events so that buildings can be resilient enough to bounce back into safe operation. These aspects are reviewed from the standpoint of some common vulnerabilities in buildings, namely, exterior doors, expansion joints, and operational energy sources.
Photo courtesy of AMBICO
Resilience is the ability of a building to maintain or resume operations during or following a severe event, including climate-related natural disasters or human-made incidents.
RESILIENT DOORS
The design and construction of wall, roof, and floor assemblies that are strong enough to withstand severe conditions is a fairly straightforward process in terms of using substantial, reinforced materials (i.e., concrete, CMU, etc.) following available standards. However, any building will only be as strong as its weakest parts, which in many cases are the windows and doors in a facade. Operable doors, in particular, which people may be using to exit, or potentially shelter behind, need to protect those people appropriately. In fact, it is the whole door assembly (door, frame, and hardware) that must be designed to work together to provide the protection needed.
Photo courtesy of AMBICO
Tornado-resistant and flood-resistant doors are increasingly sought out to protect against severe weather and are available in steel (both door types) or wood (tornado-resistant only) finishes.
To illustrate, we look at exterior doors from the standpoint of resilience in four different categories as follows:
Tornado Resistance
Resistance to both high winds and airborne debris, or “missiles,” blown through the air has been shown to be critical in resisting tornadoes or hurricanes. States within areas that are prone to these weather events have adopted standards requiring demonstrated protection as part of their localized building codes. This is predicated on the fact that, in the United States, tornadoes are the most destructive windstorm and are responsible for the greatest number of wind-related deaths annually. Further, insurance claim losses from a single tornadic event of $1 billion or more are becoming more frequent.
There are two recognized national standards for tornado-resistant doors that are part of larger standards for storm shelters and safe rooms. The first is ICC 500: ICC/NSSA Standard for the Design and Construction of Storm Shelters published jointly by the International Code Council (ICC) and the National Storm Shelter Association (NSSA). This standard is referenced in the newest building safety codes and provides minimum design and construction requirements for shelters that provide a safe refuge from storms that produce high winds, hurricanes, and tornadoes. The second is FEMA P-361, “Safe Rooms for Tornadoes and Hurricanes: Guidance for Community and Residential Safe Rooms.” This standard, supported by the U.S. Department of Homeland Security, addresses many of the same things that ICC-500 does, but is more stringent in some cases.
When specifying tornado-resistant door assemblies, the first thing to consider is a single source manufacturer with a complete package solution including the frame, door(s), and hardware. This helps with quality control and the coordination of all elements working together toward the desired end of total safety, meeting or exceeding the FEMA P-361 and ICC-500 requirements. Installation of the door assembly in the field is another important step in having a tornado-resistant door become part of a safe building. Some manufacturers offer certified installation courses to contractors because they recognize that the field installation is critical to life safety. With such a certification course, architects and owners can have some peace of mind that once installed in the field, the door assembly performs the same way it does in the testing lab.
Flood-Resistant Doors
Flooding in the United States has increased in frequency and intensity in the last 20 years whether as part of a larger storm or a stand-alone, localized event. As a result, there is a growing demand in more locations than ever for proactive solutions that can help keep flood water from entering a building through a door assembly. That usually means specifying a coordinated system of a door, frame, perimeter seals, door bottom, and threshold that can work together to withstand hydrostatic pressure and minimize water leakage.
The process of making a flood-resistant door involves attention to several details. The first is a robust system of water seals around the entire perimeter of the door. While it is common to have such seals for protecting against drafts and the general weather, water seals are usually more sophisticated and tested for the ability to resist standing water. Common solutions to help with positive sealing include the use of exterior outswing doors where standing water pushing against the door panel helps to seat the door into the frame. There are also solutions available for unseated applications which can be evaluated for their applicability in certain projects. In applications where doors are seated into the frame, standard builder’s hardware can typically be used. Where doors are unseated, special hinges and latching hardware is more often supplied by the door manufacturer.
Details of the assemblies in terms of material and make-up are also important. Galvanized steel or stainless steel are the common materials of choice which offer strength, durability, and extended life in corrosive environments. Frame options include four-sided frames, which include the threshold side in addition to the usual head and jambs. Where needed, ADA-compliant bumper or saddle thresholds are available, too. In order to ensure the integrity of the frame connection to the surrounding structure, standard or customized anchor solutions can be specified to address flood resistance. Custom engineered solutions are also available to add debris impact resistance to the door assemblies based on project-specific requirements.
Blast-Resistant Doors
Resilience also includes the need to withstand blasts or explosions, whether accidentally caused by operations, triggered by utility disruptions from severe weather, or intentionally caused by acts of terrorism. Federal government buildings around the world are required to include this aspect of resilience and safety in virtually all their exterior doors based on Unified Facility Criteria UFC 4-010-01 “DoD Minimum Antiterrorism Standards for Buildings.” This standard makes it clear that unless a door failure in response to an applied blast load does not pose a risk to occupants (i.e., the door is intercepted by a suitably strong wall before entering an occupied area) all doors must be evaluated for blast resistance at the applicable charge weights and standoff distances.
When seeking to evaluate doors for blast resistance there are two relevant standards. The first is ASTM F2927 “Standard Test Method for Door Systems Subject to Airblast Loadings.” This is a laboratory test that requires a specialized testing chamber that uses pressurized air to create the testing blast. The second standard is ASTM F2247 “Standard Test Method for Metal Doors Used in Blast Resistant Applications (Equivalent Static Load Method).” This test can be combined with finite element analysis and software to verify blast door and frame performance for virtually any charge weight, standoff, and level of protection scenario.
Door manufacturers increasingly offer blast-resistant door systems as part of their resilient design portfolio. Products are commonly engineered to meet the needed blast requirements while keeping the weight of the operable doors and frames as low as possible.
Bullet-Resistant Doors
In the United States, the threat of an active shooter situation has become a significant concern for many building types. This can be a risk in severe events as well as normal daily operations. Hence, there is often a need for bullet-resistant solutions to protect against this risk. Bullet-resistant doors and frames can be used for protection against a wide range of hand, rifle, and military attack weapons. They are available in steel doors and frames that are able to operate using conventional builder’s hardware. They are also readily available with a range of wood veneers.
Photo courtesy of AMBICO
Performance-tested, blast and bullet-resistant door assemblies are available in a range of sizes and material finishes, with options for factory or field-installed hardware. Shown here is a bullet-resistant opening meeting UL-752 level 3 performance, clad in colored, mirror-finish stainless steel, giving an ornate appearance to the building's main entrance.
EXPANSION JOINTS
During severe weather or seismic events, buildings are often subjected to loads that cause them to move in various ways. This movement is planned for in normal circumstances using building expansion joints. Since those joints are often vulnerable to the impacts of severe events, it is important they are properly addressed as part of a resilient design. Otherwise, the building itself can be directly impacted since the joints are meant to be the “relief valves” for forces allowing the building to appropriately move, absorb, or otherwise react and remain safe to use.
There are three fundamental types of forces that can act on buildings where expansion joints are needed. These include thermal expansion and contraction, seismic activity, and wind loads. Each of these are discussed further in the following sections with a focus on avoiding or minimizing damage to the building and/or harm to people.
Thermal Movement
Thermal movement in buildings is caused by daily environmental temperature changes in and around the structure. Thermal movement is primarily “one-directional” in nature and is the result of the expansion and contraction of a building as it is affected by heat, cold, and humidity levels. The amount of movement thermal joints must accommodate is defined by a structural engineer throughout the building but typically has a movement of plus or minus 10-25 percent of the nominal joint size. This aspect of resilience shouldn’t be ignored since it’s been noted that if a proper expansion joint isn’t present, there’s a good chance that Mother Nature will put one in for you – just not in ways that we are happy with.
Climate directly impacts thermal movement, so different locations will likely experience different amounts of thermal movement. A building near the equator with fairly constant year-round weather will likely experience much less variability in temperatures and humidity than, say, a building in New York City or Northern Germany. For example, if we look at a place like Ponce, Puerto Rico, which is near the equator, the temperature moves only a few degrees above or below the average of 77°F (25°C). By contrast, New York City has a 10-year average temperature swing from a low of 27°F (-3°C) to a high of 86°F (30°C) – almost 60 degrees F in difference on average. Of course, there can be days where these averages are exceeded, meaning that the total temperature swing can be well over 60 degrees throughout the year.
The significance of bigger temperature swings is that expansion joints need more area to move – the bigger the temperature swings, the bigger the need for the building to expand or contract accordingly. With average temperatures changing in many locations, that means that more expansion and contraction capacity may be needed, particularly in areas that are receiving new episodes of extended periods of extreme heat. A classic example of this type of problem is evidenced in pavement buckling in summer – the combination of ambient high heat and solar load causes the pavement to expand, and at weak points it buckles or literally “explodes.” Buildings may not experience as violent an event, but if expansion joints aren’t properly sized, designed, and installed, thermal expansion and contraction can cause buckling of surfaces such as roofs and interior floors. That can open the building to the elements and cause more weather-related damage.
The larger the structure (such as stadiums and airports) the more area that is exposed and vulnerable to thermal effects. This was a concern for architects and engineers designing a terminal expansion at the Manchester Airport in the United Kingdom. The $1.36 billion expansion of Terminal 2 made it 150 percent larger than the original to boost passenger capacity and provide gate and tarmac space for the largest jets now in operation. The new terminal also features 32 new shops and food and beverage outlets.
Architects were concerned about thermal movement creating a 7⁄8-inch (20mm) difference in floor heights across the slabs or sections of the terminal. This much difference would present a significant trip hazard for pedestrians transiting the terminal. Even worse, it could potentially be present for weeks or even months during the hottest or coldest times of the year. The solution selected by the design team was to create a project-specific “glide plate” floor joint. This custom solution had to move in three directions while simultaneously addressing the rigorous heavy-duty loads encountered in this major transportation hub. By properly accounting for all this movement, the expansion joint system was able to prevent both damage to the building and harm to people.
Photo courtesy of Inpro; Source: Prairie State Wire
Hot pavement surfaces that are not protected with proper expansion joints can buckle and “explode,” as shown on the left. Buildings with properly installed control joints, as shown on the right, help prevent such damage.
Seismic Movement Section
Seismic activity is caused by shifting of the earth’s tectonic plates causing earthquakes, tremors, etc., along fault lines. Among the complicating factors for resilient building design, seismic movement may be horizontal, vertical, in shear, or a combination of all three. That means seismic expansion joints need to be able to accommodate all these different movements. For taller buildings, the higher floors may actually move more than the lower levels as the building is caused to sway from its base. All of this means that seismic expansion joints must have the capacity for movement associated with them of plus or minus 50-100 percent.
In the United States, California and the San Andreas Fault are often thought of as the prime location for seismic activity. In reality, there are numerous seismic zones all across the country that require seismic design attention. The reasons for that activity can vary based on location, but it remains a genuine concern and resiliency threat.
It’s important to recognize that minor earthquakes are far more prevalent than severe or very large quakes such as the magnitude 6.7 Northridge quake in California in 1994 or the 9.1 magnitude earthquake (and tsunami) off Sumatra in 2004. Instead, most earthquakes are well below these levels but strong enough to cause temporary or permanent damage. Therefore, seismic expansion joint systems are best selected as products that can “reset” themselves after a minor seismic event and allow cover panels to be repositioned easily.
Note, too, that some geographic locations have seen an increase in seismic activity that has been linked to oil and gas exploration and production. Hydraulic fracturing (or fracking) may be causing pocket collapses and slippage between layers of rock that trigger small seismic events. In other cases, it appears to be something different. For example, the U.S. Geological Survey reports that beginning in 2009, Oklahoma experienced a surge in seismic activity. This surge was so large that its rate of magnitude 3 and greater earthquakes exceeded the rate in California from 2014 through 2017. While these earthquakes have been induced by oil and gas related processes, few of these earthquakes were induced by fracking. Rather, most earthquakes in Oklahoma were determined to be caused by the industrial practice known as "wastewater disposal". This is a process in which fluid waste from oil and gas production is injected deep underground far below ground water or drinking water aquifers. In Oklahoma over 90 percent of the wastewater that is injected is a byproduct of oil extraction process and not waste frack fluid.
Images courtesy of Inpro; Source: U.S. Geological Survey
The areas of the United States affected by seismic activity, and the risk of damage to buildings, are documented and available through the U.S. Geological Survey.
Wind Load Movement
Wind loading has long been understood as a factor in high-rise building conditions. Most buildings are designed to withstand wind loads up to a certain level and then are designed to sway safely in high wind events. This movement can be perpendicular and/or parallel to an expansion joint and has an impact on those joint designs. This condition is common where a low horizontal building span meets with a taller vertical element, such as the lobby of a hotel with an adjacent a high-rise component. Movement in these joints is typically 50 percent or so.
Over time, the normal anticipated effects of wind pressure or the impact of a severe wind event on the sides of buildings can lead to some serious issues. These can include torsion forces or swaying of the building at the very least. That can lead to cladding erosion or failure or structural failures due to excessive wind loading. Hence, in the interest of designing a resilient high-rise structure, it must be able not only to withstand high wind loads, but also to work with them. That means that, as with seismic activity, expansion joint systems should be able to “flex” and yet remain in place as the building sways or torques. That way, the expansion joint covers can remain in place and the integrity of the building materials can be maintained.
For all of these different conditions—thermal, seismic, and wind—architectural expansion joint solutions are available that can help buildings handle movement. This helps them retain their structural integrity, protect people and property, and provide a more resilient means to keep the building functional and aesthetically intact.
Photo courtesy of Inpro
The impact of wind on high-rise buildings needs to be addressed not only in the structure but in the type of expansion joints used to address building sway.
PROPANE AS A RESILIENTENERGY SOURCE
Propane is a well-known and commonly available fuel that is often used because of its versatility. In locations where other options aren’t available, such as rural, agricultural, or off-grid areas, propane can be delivered and stored on-site to provide a reliable energy source. Although commonly stored in liquid form in pressurized tanks, it is dispersed as a gas that is similar in performance to natural gas.
From a resiliency standpoint, propane can fuel a building’s vital systems, including power generation, space heating, and water heating. That can be significant during severe weather events or other disruptions since it can allow the building to continue operating at times when it may be needed most. If the electrical supply to the building is disrupted due to a power outage, standby generators fueled by propane enable the people in the building to still function by providing uninterruptible power. On-site generators can also protect critical systems, including security, refrigeration, lighting, automatic doors, and IT systems, in addition to heating and air conditioning. At the same time, propane-fueled appliances such as water heaters, can continue to operate without interruption. In the past, commercial standby generators were typically powered by expensive diesel fuel. Today, manufacturers offer several affordable, propane-fueled standby generators that are powerful enough to serve a variety of commercial building sizes, with capacities of up to 400 kW – 2.5 MW of electricity.
Image courtesy of Propane Education and Research Council (PERC)
The relative environmental impact of propane compared to other fossil fuels, including electricity from coal-fired plants, is shown in this graph.
Environmental Characteristics
According to the U.S. Environmental Protection Agency (EPA) “LPG (propane) is considered a clean fuel because it does not produce visible emissions. However, gaseous pollutants such as nitrogen oxides (NOx), carbon monoxide (CO), and organic compounds are produced, as are small amounts of sulfur dioxide (SO2) and particulate matter (PM).” The EPA goes on to point out that some of the factors contributing to those small amounts of pollutants have less to do with the actual fuel and more to do with equipment, including burner design, burner adjustment, boiler operating parameters, and flue gas venting. Further, things like improper design, blocking and clogging of the flue vent, and insufficient combustion air need to be avoided.
Compared to other options, such as fuel oil or diesel-powered generators, propane is a cleaner fuel that can reduce CO2 emissions. That is also true compared to grid-provided electricity that is produced in coal-fired generating plants. Propane use can also be cheaper to use than some of the more polluting alternatives. For example, a YMCA facility in the state of Maine switched from using heating oil to propane for its space and water heating, resulting in a CO2 emissions reduction of 183,000 pounds per year — the equivalent of taking 17 cars off the road every year. Similarly, a propane condensing tankless water heater can save building owners or operators up to 50 percent on their water heating costs when compared with the costs of operating a standard electric storage tank heater.
For greater reductions in emissions and environmental impacts, propane can be used as a supplement to other on-site energy sources. In cases where solar photovoltaic panels or wind turbines are used to generate electricity off-grid, a propane generator can provide auxiliary power when solar or wind is not available or when stored battery voltage cannot meet the electrical needs. Similarly, propane can be a supplemental fuel for commercial solar thermal systems which store solar-heated water, provide efficient backup heating at thermal efficiencies greater than 95 percent, and offer controls that easily integrate with upstream solar systems to control flows and temperatures. Biomass fuel systems, including wood, pellets, dry shelled corn, and other indigenous plant materials, typically require an auxiliary system for times when the fire is out, or the biomass system is unable to meet a variable heating load. In those cases, propane’s flexibility makes it an excellent energy source.
Photo courtesy of Propane Education and Research Council (PERC)
Propane-fueled combined heat and power (CHP) systems help commercial buildings control energy use and cost on-site, plus provide a significant amount of grid-free resiliency.
Combined Heat and Power Capabilities
The ability to generate both heat and power on-site is attractive in a number of situations both for normal operations and in terms of resilience. Such combined heat and power (CHP) systems can use a propane or natural gas engine, heat exchanger, and generator to create electricity that powers the building. Simultaneously, the heat from the unit is captured by the heat exchanger and used to channel thermal energy to applications like space heating, domestic water heating, dehumidification, or other loads such as swimming pool heat. Utilizing both the electrical and thermal output of the propane CHP system achieves system efficiencies as high as 75 percent, while typical stand-alone electric generation from the grid is only about 30 to 50 percent efficient.
In commercial settings, CHP systems can greatly improve energy efficiency when compared with traditional systems. These systems are most effective in buildings with significant and steady thermal demands, which could include heavy domestic hot water needs (e.g., hotels, hospitals, car washes), swimming pool heating, or space heating through a hydronic system. CHP systems can also be ideal for retrofit situations when existing water heating equipment needs replacement, electric rates are increasing, or on-site power generation is an increasing priority. From a resiliency standpoint, most CHP systems can be used for standby power during grid-based power outages.
In many states it is even possible to sell extra electricity produced by the CHP system back to the energy grid. Where this “net metering” is permitted, these programs allow utilities to issue kilowatt-hour credits to customers, who can use them to offset any electricity consumed from the grid. In most cases, the transfer is accomplished through a bidirectional meter. The meter turns backward as excess electricity is sold to the utility. Optimized CHP systems can synchronize with utilities to operate when electric rates are highest, maximizing cost savings.
Overall, propane has been used and viewed favorably by design professionals and others as a fuel choice. Dan Weber is an architect at Anacapa in Santa Barbara, California. He notes “In rural residential projects, [propane] is just the status quo. Everyone uses propane because it’s really reliable and the cost is low. I was surprised that it was really not that expensive to do a subterranean propane tank." Related to resilience, Alex Wilson, founder of BuildingGreen and the Resilient Design Institute has stated "Propane is a good option for backup generators and offers the prospect of resilience.” Whether used as a stand-alone fuel with lower emissions than some other options or an auxiliary to clean, renewable systems, propane is a viable option.
Conclusion
Strategies have been presented for achieving better resilience in buildings. Doors that are designed and fabricated to withstand wind, flooding, and blasts help protect people on the other side of them. Properly designed and installed expansion joints and cover systems allow buildings to move and be fully operational following thermal, wind, or seismic events. On-site power generation such as can be provided by propane offers continuity in operations during utility service interruptions. Taken all together, these strategies help form an overall, holistic approach to building resilience.
Peter J. Arsenault, FAIA, NCARB, LEED-AP is a nationally known architect and a prolific author encouraging more resilient buildings through better design. www.pjaarch.com, www.linkedin.com/in/pjaarch
