As you are certainly aware, on June 24, there was a disastrous collapse of the 12 story Champlain Towers South condominium building in Surfside, Florida. It may be some time before we know all the factors related to what caused a modern building to fail but it is almost certain that the local weather and environment played a part, even if it was over an extended period of time.
One major factor is certainly seawater.
When seawater enters into the pores of concrete and reaches the reinforcement then corrosion will occur. It will affect the durability of the structure. Seawater reacts chemically with constituents of cement concrete which results in damage to the concrete structure in several ways. Corrosion of reinforcing steel and other ferrous metal is also one of the biggest causes of deterioration in coastal construction projects. The invasion of salt and moisture -- inevitable near the ocean -- results in accelerated corrosion of reinforcing steel, weakening the overall structure.Higher temperatures advance the deterioration.
The High Price of Weather
Hurricanes are the costliest disasters in the past half-century, accounting for $25.7 billion in damage from 1960 through 2014 in New York alone.
A few other examples.
- 2012 - Hurricane Sandy which is estimated at $10 billion dollars.
- 2005 - Hurricane Katrina is estimated at $100 billion in damages
- 1992 - Hurricane Andrew is estimated as having caused $46 billion in damages
Flooding ranks second in total damage.
A study published recently in the Proceedings of the National Academy of Sciences journal says that from 1988 through 2017, intensifying precipitation was responsible for a total of $75 billion in U.S. flood damage over the 29-year study period. Total flood damage in those years was nearly $200 billion, accounting for more than a third of the damage in that period.
In another more regional example, from 1960 through 2014, every county in New York suffered at least one flood that caused damage to buildings.
Data also showed that severe storms were the most frequent event, but accounted for only 16.8% of total damage statewide. Winter storms were the most economically significant hazardous events in the regions surrounding Lakes Ontario and Erie, causing the highest per-event property damage in places like Rochester and Buffalo.
After Hurricane Sandy the FEMA sent a team to New York and New Jersey to evaluate building damage and recommend changes to engineering codes to minimize future damage. One of their recommendations, elevating buildings above the base flood elevation, has now been incorporated into the New York City Design Guidelines.
Raising the first floor of a building isn’t the only way to protect it from high water. Another strategy that is being incorporated into buildings across New York state is wet floodproofing. This approach will allow floodwater to enter a structure without causing damage. This requires firmly anchoring a building to the ground, flood-resistant materials in areas that will be underwater and protecting mechanical and utility equipment. It also, by design, uses openings to let floodwater escape.
Although hurricanes and flooding cause significant damage to structures, we can’t ignore the impact on people. Heat waves kill upwards of 600 people every year and frequently, these deaths are tied to power losses that shut off critical air-conditioning systems. Rethinking the design of building walls and roofs to protect occupants – an approach called “passive survivability” - can help maintain critical life-support conditions during an extreme heat event.
These resilience strategies can easily be applied to new buildings. They should also be considered as retrofits for existing buildings where people may shelter in place during extreme weather, such as community centers.
Each year, construction and preservation projects suffer billion dollar losses due to weather-related project delays and mishaps. There are also dangers to workers.
On Site Considerations
- High Heat Material Efficiency - Employee safety
- Dry Conditions - Fire safety and dust
- Rain - Material damage, employee safety from electrical accidents
- Air Quality - Employee health
- Wind - Lifting operations, material damage
- Low Visibility - Cranes
- Low Temperature - Bricks, concrete and glazing
Companies are now using hyperlocal weather forecasting to improve the efficiency of planning and communication procedures so that they are well prepared to deal with any weather events that may arise.
Natural ventilation, daylighting, rainwater harvesting and other “climate-responsive” strategies are hallmarks of sustainable design because they take advantage of freely available, inexhaustible resources. Working with nature is all very well as long as nature is fairly predictable, but in a changing climate, that’s no longer the case. As temperatures and humidity levels rise, and as wind and precipitation patterns fluctuate, climate-responsive buildings may no longer keep up.
As an example - what if, 20 years from now, night flushing is no longer possible? What if the mechanical equipment, designed for today, becomes overwhelmed by heat waves happening throughout the year?
Night cooling, also known as passive cooling, covers all natural processes and techniques of heat dissipation and modulation without the use of energy. Preventive techniques aim to provide protection and/or prevention of external and internal heat gains. Heat dissipation techniques allow the building to store and dissipate heat gain through the transfer of heat from heat sinks to the climate. This technique can be the result of thermal mass or natural cooling.
Whether buildings rely on natural or mechanical ventilation, maintaining acceptable levels of efficiency, comfort, and durability will likely become more difficult and expensive as weather patterns change. Buildings not designed with the future in mind could become impractical to operate but trying to design for the future does include a great deal of uncertainty. Fortunately, experts are developing new ways to model weather and more flexible methods of predicting building performance.
When You’re Expecting Climate Change
We’ve all heard about the projected impacts of global warming but global climate scenarios vary, and modeling how the effects might play out by region—let alone on a particular building site—is a developing science where results cannot fully be verified until it’s potentially too late.
Should designers upgrade to the next level or protection?
Just to look at one example -culverts. Culverts come in a number of sizes. How much does it cost to upgrade to the next size, or the next? Could this be insurance worth investing in? Many upgrades aren’t very expensive and the budget can potentially tolerate upgrading to exceed the current standard.
It may seem hard to believe but the shape of city buildings, how they are arranged, and the heat they generate all affect the local weather. Being able to model the complicated processes enables engineers to improve the energy efficiency of the buildings they design. In the past, buildings were mostly built without taking into account the features of a city's weather patterns or the influence that city buildings can have on the weather. The new goal is to develop programs that combine weather forecasting with models that measure the effect of heat released by buildings.
The widespread acceptance that flooding will continue to become more frequent and costly around the world is driving an urgency in the design and planning community. Not only is the climate more volatile, but land shortages continue to encourage the construction of buildings in flood-prone areas. Houston’s Harris County alone permitted more than 8,600 structures to be built in 100-year floodplains—land where floods have a 1-percent probability of occurring in any year.
The disaster in Surfside may lead inspectors to develop ways to better inform the owners of existing buildings of the typical weaknesses in the load bearing elements of their structures caused by the changing climate and weather. Along with the warnings may come corresponding instructions and new requirements to remedy potentially dangerous scenarios. At the same time, there is a need to inform construction technicians of recommended future-oriented design parameters, such as maximum snow load, wind speed, temperatures, potential durations of future heat waves and the maximum precipitation a building should withstand.
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