With the building sector accounting for nearly 40% of global carbon emissions, achieving net zero is a challenge that’s increasingly top of mind for AECO (Architecture, Engineering, Construction, and Owner) professionals. It’s not just the design and building industry that’s pushing for change—from the public to politicians, reducing our carbon footprint is a priority for many.
Of course, working or living in a building that does not release any carbon emissions is a very worthwhile goal. This is evident across the nation. Architecture 2030 seeks a 50%-65% reduction in carbon emissions by 2030. SE2050, representing structural engineers, has similar goals. And many states and cities have similar stated thresholds for 2030 and 2035.
Though there is much written about net zero, and there are several similar groups who are rating and advocating for greener building practices, the truth is that so far in much of the northern half of the country, we have very little commercial building stock that is clearly in the net zero realm. Architects are keenly aware that the devil is in the details, and they also need to help decipher what the additional upfront building costs might be per specific building project to achieve net zero, or at least be net zero ready.
There are two issues as we look towards 2030: existing buildings and new construction. For the purposes of this article, we will focus on new construction.
For a commercial building of 3+ stories, how can we best achieve net zero carbon while also limiting additional upfront construction costs? And how, where, and why might masonry and tile fit into this equation?
- It would be wise to strategically consider how to and reduce a building’s Window-Wall-Ratio (WWR), as the WWR is one of the key criteria in a building’s energy usage.
The US Department of Energy (DOE) has much to say about this topic, in its 2015 report Building Energy Asset Score: Program Overview & Technical Protocol. The report looks at 18 different building types and analyzes the relative importance of different criteria on building energy usage. While interior lighting power density ranks near the top, a building’s WWR is in the top 4 criteria in 61% of all building types.
For most buildings where the design aesthetic is calling for glazing to be over 70% of the wall area, triple glazing is often needed, and sometimes fixed exterior louvers to help reduce solar heat gain.
- Consider and implement designs with thermal mass to reduce peak heating and cooling demand. Groups like the Passive House Institute (PHIUS) https://www.phius.org/home-page encourage passive building principles that can function without complexity and even when the power might go out. Thermal mass is an attribute where a material absorbs, stores, and slowly releases heat. Masonry and tile products naturally exhibit significant thermal mass, which can be taken advantage of whether designing an exterior wall or an interior ceramic tile floor layout. This will become even more important in the future if we see more rolling power blackouts, natural disasters, or other emergencies.
- Building heights also have a significant effect on energy efficiency. Are we entering an era where we will not see many new 20, 30, or 60-story buildings?
Ann Edminster (The New Carbon Architecture) states that the most energy-efficient building height is between 6 and 12 stories. Similarly, per a report by Adrian Smith + Gordon Gill Architecture, the ideal building height for energy efficiency is 4-story within a courtyard layout.
Structural masonry can be easily designed to accommodate a building of 10 stories, which falls in line with these recommendations for top energy efficiency.
- Think longevity. A key point regarding green building is how long will the building remain before it likely will be torn down? In order to reduce demolition and landfill needs, designers need to carefully consider the life expectancy of common building materials. According to the “Recommended Guidelines for Building Component Lifespans in Whole Building Life Cycle Assessment” by the Carbon Leadership Forum (2018), these are the likely lifespans of common exterior envelope elements: https://www.carbonleadershipforum.org/wp-content/uploads/2018/07/CLF_Recommendations_BuildingComponentLifespans_07-06-2018.pdf
Precast Concrete Panels: 30+ years
Metal Curtainwall: 30+ years
Glass Curtainwall: 30+ years
Brick / Stone / Concrete Block: 50+ years
These are some of the key concerns and opportunities that the industry is grappling within 2021 and beyond. The decisions we enact now, like State Energy Codes/Addenda and municipal bylaws, will have far-reaching repercussions. The masonry and tile industry stands ready to be part of these design and construction conversations as we plan and build for the next generation.