Many of us use GPS navigation systems to help us find our way to unfamiliar destinations. But what happens if the directions are wrong because the maps are old and outdated? We get lost. Similarly, many of us use energy models as part of our design process in the belief that they will help us understand how our building will perform and operate over its lifetime of perhaps 60 years or greater. The problem is these models use outdated climate and weather data. We design buildings and develop energy models based on current climate zones, but the most recent weather files from the National Renewable Energy Laboratory (NREL) date from 1976 – 2005. This data only tells us where we have been, not where we are going.
Our climate is changing – and changing faster than many have forecasted. The latest International Panel on Climate Change (IPCC) Report shows that the historical average temperature increase between 2011 and 2020 was 1.09 degrees Celsius with no signs of slowing down and every sign of speeding up. What we believed might occur by the end of the century may, in fact, occur by 2040. The IPCC reports with very high confidence that “global warming, reaching 1.5°C in the near-term, would cause unavoidable increases in multiple climate hazards and present multiple risks to ecosystems and humans.” If climate change continues unfettered, it will cause degradation to the world’s forests, coral reefs, and coastal wetlands, as well as a loss of biodiversity, access to fresh water, agriculture, food production, and security. Furthermore, climate change will impoverish at-risk populations and degrade infrastructure, and have significant impact on air quality, thermal comfort, and health.
The changing climate has a direct effect on local weather patterns. Not only is extreme weather becoming more common, but there is also a general warming across all climate zones that will have unprecedented effects. For example, the climate of the upper Midwest is projected to be somewhere between the current-day climates of Tennessee and Alabama in as few as 40 years, and certainly by the end of the century. Depending on the climate zone, things may be hotter, cooler, wetter, or drier – in any combination. Each climate zone faces a similar challenge – our historical climate and weather data cannot serve us now, let alone 20 or 30 years from now. Our buildings and systems will be stressed and overtaxed, leading to higher energy use and carbon emissions, further accelerating climate change.
This creates a unique challenge for the design and construction industry. We must design to current energy codes and environment, while considering future changes in climate and weather. We must design buildings that both perform well today and are ready for expected tomorrows.
The codes we must design to and the tools we use all incorporate outdated weather files and there is not a standard or “centralized database of future weather files that are in a format that can be used in energy models.” We may believe that designing for current conditions allows us to meet the demands of today, and that by the time our mechanical systems need to be replaced in 20 to 25 years, we can swap them out for systems that meet the requirements and needs of the time. This may work for mechanical and electrical systems, but a building’s massing, orientation, glazing and shading strategy, and envelope design also play a significant role in determining its performance. Will the buildings we are designing now be able to withstand the temperature increases and other weather-related extremes of the next 25 years, let alone the next century?
Consider Future Climate and Weather for Resilient Design
I am a staunch advocate of designing beyond the code – not letting the minimum requirements of any code become the maximum to which we design – and of basing decisions on the long-term value of a thing rather than just its first cost. However, in a changing climate there may be instances when this may not be the best course of action. Take insulation as an example. In Appleton, Wisconsin (ASHRAE climate zone 6A) the current commercial energy code (IECC 2015) requires a minimum R-Value of a metal framed wall assembly of R13 + R7.5 ci, a roof assembly to be R30 ci. Normally, I might explore increasing those values to R24+R10ci and R36+ci respectively to increase the building’s performance within reasonable payback periods. However, if future climate scenarios show that our future climate will behave more like Atlanta, Georgia (ASHRAE climate zone 3A) which currently requires R-Values of R13 + R7.5 ci and R25ci, it may make more sense to focus more on the weather resistive barrier, shading and cooling strategies, and filtration and ventilation rates.
Consider Using Future-Focused Weather Files
Until we have standardized “click this button” forward-thinking global climate projections and Typical Meteorological Year (TMY) files that reflect hour-by-hour temperatures, wind speeds, and humidity levels readily available in our energy modeling software, we will need to blend localized data with available files and interpret them as best we can. Another source to consider is purchasing EnergyPlus Weather Files (EPWs) from WeatherShift – a tool developed by Arup. EPW files contain hourly values of key weather variables for a typical year and are intended to be used for simulating building energy requirements. The Weather Shift™ tool uses data from global climate change modeling to produce EPW weather files adjusted for changing climate (heat and rainfall) conditions. The projected data can be viewed for three future time periods based on the emission scenario selected.
There are other resources available if one is ready to dig into climate science. The climate tools, maps, and data available on the National Oceanic and Atmospheric Association (NOAA) Climate’s website are exhaustive. The U.S. Climate Resilience Toolkit provides case studies, tools, training courses, and steps for risk assessments for each region of the U.S.
Design for Flexibility
Above all, we need to design our buildings to be flexible – conducive to change and updates. We may need to design our buildings using more of an assembly and component systems approach, allowing us to assemble and disassemble, re-use, renovate or re-locate our buildings. A warming climate should lead us to consider a move away from the use of natural gas and other fossil fuels for heating, and toward the electrification of systems for both heating and cooling, connected to local area utility micro-grids served by regional renewable energy infrastructure. We would do well to design buildings conducive to such a shift. We need to stop designing our buildings using historical weather data and instead design for the future, because the future is now.