Back in February we discussed Sensible Rebuilding and HVAC Installation with Future Flooding in Mind. According to this New York Times article, the Intergovernmental Panel on Climate Change, a panel of renowned international scientists, has determined that because of human activity causing global climate change, it is conceivable that we will have a 3 foot rise in sea levels by the end of this century along with a 5 degrees average temperature increase over land (and possibly 10 degrees at the poles). We can argue among ourselves regarding the merit of scientific claims of global warming, but it has become a generally accepted fact to the majority. How then do we prepare our environment and design our spaces for such change?
Architects, engineers, designers, builders and contractors are advised to study FEMA’s new Advisory Base Flood Elevation designations. These maps are being developed with flood hazard data accumulated from Sandy. An interactive map can be accessed by using FEMA’s BFE Map Lookup Tool. ABFEs (Advisory Base Flood Elevation) can help communities and property owners make informed decisions about rebuilding their homes and businesses to reduce their vulnerability to flooding. They provide an indication of how flood elevations and risk zones are likely to change in the near future. For coastal building in flood zones, National Flood Insurance Program building requirements are being raised from 4 feet to a minimum of 8 feet above grade and a recommendation of 6 feet above BFE.
As previously discussed, it will be imperative for all coastal structures to install utilities and HVAC systems and ductwork above the Designated Flood Elevation (DFE). FEMA’s projects that “with most outdoor HVAC equipment, the main issues presented by floodwaters are inundation, velocity flow, and debris impact. The control and power circuits and mechanical parts in HVAC equipment, even when they are designed for outdoor installation, are not designed to withstand inundation by floodwater. They are also not designed to withstand the dynamic forces of high velocity flow and debris impact. During inundation, the electric and electronic control and power units would likely short-circuit, and the mechanical equipment would fail to operate and may be torn away. Most of the metal components would eventually corrode and deteriorate, especially in areas inundated by floodwaters containing salt. High velocity flow in either riverine or coastal areas can dislodge equipment from their stands and separate connecting pipes, hoses, and power lines.” Basically, the recommendation is to elevate all equipment and ductwork above the DFE and to constrain it to prevent movement.
So, going forward, what will be the effect of climate change on outside air design temperature for air conditioning load calculations? Typically, ASHRAE reviews these every 10 to 15 years or so, but rapid climate change may require more timely analysis. Hopefully, increased efficiency standards and envelope insulation standards will act as progressive counteractions and prevent cooling loads from creeping up due to incrementally higher outdoor dry bulb temperatures.
Clearly, climate change is having an extraordinary effect on the way we design and build. Unfortunately, this will also inevitably add additional cost and bureaucracy to the construction development process if we cannot stem the tide of environmental change.