About a dozen or so years ago, architect William McDonough and chemist Michael Braungart attempted to apply the Cradle-to-Cradle (C2C) concept to buildings, with a list of charter guidelines including:
- Incorporate technical and biological nutrients that can safely become reusable feeders.
- Measurable use of renewable energy. Examples of renewable energy include solar, terrestrial, and wind heat exchange, wind energy, biomass, hydropower, and photovoltaic.
- Anticipate evolution and change, integrating strategies and approaches that enhance the building’s ability to adapt to a variety of uses over time.
Not much has come of the Cradle-to-Cradle charter, but Apex Plaza — an 187,000-square-foot mixed-use building in Charlottesville, Virginia, designed by William McDonough + Partners — shows that these principles have not been forgotten. In fact, the principles have been extended to what they call the Five Commodities:
- Good materials: including mass woods and low carbon options.
- Good Economy: Design for Adaptation and Disassembly.
- Good Energy: Fully electric and net positive with 436 MWh of solar power on the roof canopy, high performance glazing, and high performance rain screen cladding.
- Potable water: The captured rainwater is reused in landscaping.
- The Good Life: Biophilia, “Beauty from Simplicity”, Rooftop Landscaping, and Views.
Buildings’ carbon footprint is the architectural issue of our time, and design partner Alastair Reilly has shared a document with Treehugger that shows how they categorize the different types of carbon emissions, including front carbon – I like to use them prominently up front – emitted during the product and construction phase and the operating carbon that comes from Run the building. But they are also very focused on end-of-life carbon and really bypass the life cycle with recovery and reuse.
This is one of the reasons why this building is so interesting. It is not just a monument as another huge wooden building. Although it has some of the largest and most branched woods we’ve seen at Treehugger, there’s a lot going on.
There are many benefits to using mass timber, including faster construction and reduced mass. But the biggest factor is the low carbon emissions offered, as can be seen in this comparison of concrete and overall wood construction. Using wood avoids greenhouse gas emissions by 809 metric tons of carbon dioxide (CO2) compared to building with concrete, which would be much greater if there was not a significant portion of the carbon up front in the concrete pallet and multi-level carport.
When asked why there was so much parking and why a portion of it was top grade, Riley told Treehugger that the site was previously a rooftop parking lot for an adjacent building, and that lost parking must be accommodated as well as legal parking requirements for the new space. Riley noted that they had already requested a reduced parking requirement, but the request had been denied. However, the car park has been designed with ramps on the outside and flat car parks so that it can be converted to other uses in the future.
Can a building be carbon positive?
The Riley document also claims that the building is “going beyond zero carbon and moving towards positive carbon.”
“Carbon sequestration is an important component of construction with cross-laminated timber. Forests act as a carbon ‘sink’ where healthy trees remove carbon dioxide from the atmosphere, release oxygen and capture/store carbon. Using sustainably harvested FSC wood block reduces carbon footprint By storing carbon dioxide in the same way a healthy tree might (one cubic meter of timber stores about one ton of carbon dioxide).”
They go on to claim that 2,091 metric tons are stored in wood and 809 metric tons are avoided by not using concrete, for a total of 2,990 metric tons of potential carbon benefits. This is controversial, roughly indicating that the carbon storage offsets the concrete when the trees were doing a good job of storing carbon when they were standing in the forest. Some, like Paula Melton of BuildingGreen, note that “so much carbon in forests is stored in and under the soil, and it’s unclear how much carbon and methane (a more potent greenhouse gas) is released at harvest.”
As engineer Will Hawkins writes in Wood and Carbon Insulation, “The accounting of trapped carbon is often a source of controversy, confusion, and inconsistency. When insulation within Unit A is reported, [in the upfront carbon] Or beside them as negative emissions, it can create a counter-intuitive impression that using timber excessively can have environmental benefits.”
This is why I don’t like the term “carbon positive”. As Hawkin notes, “It’s still better (for the climate) that you don’t build anything at all from a building out of wood.” It’s great that you avoid 809 metric tons of CO2 by changing from concrete; Let’s not go tulips.
Detachable and flexible design
The building is designed with mechanical fasteners so that at the end of its life it can be disassembled relatively easily. Reilly is already thinking ahead of the next project, where he will have mechanically installed cement panels for sound insulation instead of the gypsum concrete used here.
But disassembly is still a long way off. Most of the buildings are demolished because they are functionally outdated. This is unlikely to happen here.
One of the reasons the wood block is so chunky is that they wanted a long span and vertical grid designed for flexibility so that it could be adapted to different uses. Reilly shows a typical office floor plan, but is designed so that it can be converted to residential use if the market changes.
The gorgeous exposed wood is FSC certified by Nordic Structures in Quebec and delivered by train. Nordic has the first Cradle to Cradle-certified collective wood products on the market in North America, which means they are evaluated against criteria including material health, material reuse, renewable energy, carbon management, water management and social justice.
McDonough noted, “It’s great to see manufacturers of a critical product for circular buildings committing to Cradle to Cradle.” He is right ; I hope to do more companies. Silver is not the highest level of certification, but there were apparently some emissions of VOCs (Volatile Organic Compounds) in the plant itself from the adhesives before it was fully installed.
Group timber buildings are almost becoming commonplace, and they only seem to catch attention these days when they’re the biggest, tallest, or weirdest. Apex Plaza is not one of those but it is certainly among the most interesting because of its design for the flexibility, dismantling and circularity of the future and because of the all-electric heating and cooling, solar energy, and the concern for health and wellness-to be today.
It’s also a great example of what I call my Ironclad Carbon Base: “As we electrify everything and remove carbon from the electricity supply, emissions from embodied carbon will increasingly dominate and approach 100% of emissions.” This is an all-electric building with its energy coming from Apex renewable supplies and from rooftop solar, so nearly 100% of its life cycle emissions will come from initial carbon emissions and subsequent embodied carbon emissions.
If you take the position that you shouldn’t claim credit for storing carbon in the wooden structure – as I do – the primary carbon emissions from this massive parking garage dominate the project’s carbon profile. At 1,445 metric tons of CO2 (shown in the graph above), it’s no small picture.
Now that we have the technology and building codes that allow us to build above grade low carbon structures, it’s time to change zoning codes and planning to reduce or eliminate concrete parking lots. As always, it’s the cars that are killing us and you can’t be carbon positive your way out of this with a pile of wood.