Last week marked the start of the United Nation’s 28th Conference of the Parties (COP28), the annual meeting to review progress and update plans for addressing climate change. It provides an opportunity to assess the progress being made and where the gaps are. It also provides insights into new concepts, approaches, and opportunities for driving the deployment of high-performance buildings and façades.
One such insight is the large impact of refrigerants in building cooling systems. These and other impacts of mechanical systems are often neglected in building life cycle assessments, to the potential detriment of investments in building envelope efficiency improvement.
The Economic and Health Impacts of Climate Change are Increasing
The new International Panel on Climate Change’s Climate Change 2023: Synthesis Report states, “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850-1900 in 2011-2020.”
We are already seeing the economic and health impacts through many weather and climate extremes in the U.S. as well as across the globe. The National Center for Environmental Information reports: “In 2023 (as of November 8), there have been 25 confirmed weather/climate disaster events with losses exceeding $1 billion each to affect the U.S. Overall, these events resulted in the deaths of 464 people and had significant economic effects on the areas impacted.”
By comparison, in the 1980s, there were only an average of 3.3 such events per year (consumer price index – adjusted), and the average for the most recent five years (2018–2022) is $18 billion events per year.
We are Still Not on Track…
We are still not on track (like this time last year) to meet the COP21 Paris Agreement’s target of limiting global temperature rise to only 1.5oC. And limiting warming to 2oC is going to be a challenge. According to the World Resources Institute, “Progress made in closing the global gap in climate action remains woefully inadequate—41 of 42 indicators assessed are not on track to achieve their 2030 targets.”
But We Are Going Faster Than We Think…
There is some good news: The recent International Energy Agency’s (IEA) Breakthrough Agenda report suggests that progress is faster than we think, with transformation happening in the U.S., China and Europe.
The transportation segment is on track to meet 2030 targets through significant financial incentives for investments in and availability of electric vehicles (EVs). EV sales are expected to comprise 18% of new car sales in 2023, and at current deployment rates, the needed 65% target will be achieved before 2030.
Solar and wind power are also expanding rapidly, with costs reduced by 89% for solar photovoltaic (PV) since 2010. The IEA predicts that total fossil fuel use will likely peak in 2025 and will decline by an amount approximating the lifetime output of a large oil field annually. While this is not yet on track for the 1.5oC target, some technologies such as batteries, solar PVs and electrolyzers for hydrogen production are reportedly moving fast enough to support more stringent targets.
Building Sector Progress is Way Behind
The number of new buildings globally that meet net-zero performance was less than 5% in 2022, yet new construction needs to be 100% net zero by 2030. Growth in construction–especially in the developing world–is offsetting the 6% reduction in energy use intensity that has been achieved since 2015, causing emissions to continue to rise by an average of 1% per year.
Below are some of the IEA recommendations for governments to realign the building sector:
- Harmonize and upgrade definitions for net-zero emissions and resilient buildings and their assessment processes;
- Create and strengthen procurement commitments for net-zero and resilient buildings;
- Increase the scale of funding for net-zero and resilient building projects; and
- Identify and overcome knowledge gaps for deployment through collaborative research and development, best-practice identification, communication and industry expertise capacity building, leading the way through government projects.
Initiatives to address some of these ideas have been created in the U.S. and Canada at the national, state/province and local levels. Still, more must be done to accelerate the deployment of high-performance buildings. Putting large investments into heat pump development and deployment is helpful but insufficient. An emphasis on building envelope performance is needed to enable building electrification and heat pump deployment.
The impact of government support, tax incentives and private sector action for EV deployment in the U.S. is impressive. What would similar targeted investments do for market deployment of net-zero buildings?
Support for an Envelope-First Approach
Project Drawdown has identified individual emission reduction solutions and their impact on reducing greenhouse gas emissions. The graph shows the relative impacts of different individual building-related solutions.
It is encouraging that two key envelope-related strategies–insulation and high-performance glass–are ranked above high-efficiency heat pumps in impact.
Unfortunately, addressing thermal bridging through window frames, which can significantly degrade overall fenestration assembly thermal performance, is forgotten in this analysis. The “insulation” strategy is based on moving to passive house insulating performance and reducing embodied carbon through low-carbon materials.
Ignoring Refrigerants Penalizes High-Performance Envelope Investment
Interestingly, refrigerant management and low-emission refrigerant alternatives provide some of the largest impacts (although the estimates cover both industrial refrigeration uses and building cooling). Reductions in embodied carbon can be made by reducing the size of heating, ventilation and air conditioning (HVAC) systems by investing in better envelopes (which often require more embodied carbon). This is an overlooked net carbon benefit for investing in high-performance façades, which can only be identified by doing a robust whole building life cycle assessment (LCA).
However, a recent study by LMN Architects, which identified the global warming impacts of commercial HVAC systems, reported that “nearly all so-called ‘whole building’ LCAs omit emissions from the material used for air handling units, ductwork and piping, terminals, electrical systems and the impacts of refrigerants.” This omission can significantly disadvantage upgrade decisions relative to the building envelope whose components have known embodied carbon, which is always included in LCAs.
LMN Architects states that even without considering refrigerants, the embodied carbon of mechanical, electrical and plumbing systems may contribute approximately 10-25% of a new building’s embodied carbon and 50% or more of a renovation. For reference, the embodied carbon from a façade in new construction is often approximately 15%.
High-performance envelope energy-efficiency strategies that increase embodied carbon (like triple-pane glazing or double-skin curtainwall) may not be seen as having a net carbon benefit if the real carbon impacts of the HVAC system’s size reduction are not considered. Indeed, when envelope performance is sufficiently good, it may be possible to eliminate perimeter heating and cooling systems without compromising comfort.
Accurately quantifying the embodied carbon savings in HVAC system elimination or down-sizing is critical to informing appropriate high-performance design choices for the envelope.
Resilience Comes Front and Center
Next month, I’ll review the notable appearance of building resilience alongside net-zero targets in global climate change-related recommendations. The U.S. has already begun to act in this area through the Department of Energy.
A recently published study from the National Laboratories explores the impact of adopting higher stringency building codes on the passive survivability of residential buildings–single-family homes, multi-family apartments and assisted living facilities–during severe weather events. This initiative seems to attempt to quantify the link between building energy performance and life safety–a topic I have advocated for previously–to provide further incentive for jurisdictions to adopt more stringent energy codes.
Thank you for sharing this.