A building envelope is the armor that protects inhabitants, as well as interior finishes, furnishings and equipment. In the walls, roof, flooring, healthy materials are important to anyone suffering respiratory problems, like allergies and asthma. A well-designed home envelope is durable, healthy, insulating, and tightly sealed. Panelized construction homes are engineered to bring these qualities together.
In a well-sealed building, fresh air is provided through controlled ventilation systems, ensuring occupants breathe healthier, filtered air, and removing pollutants produced inside the home (dust, CO2, natural gas byproducts, etc.). Heating and cooling are maintained more efficiently and more comfortably, without leaking conditioned air through gaps in doors, walls, and ceilings. This means no drafts or ingress of polluted air, particularly during pollen or smoke advisories! SIPs have uniform insulation, which means there are no cavities where moisture might accumulate and promote mold, mildew, or rot.
Where you’re stopping air leaks you’re also blocking noise transmission pathways, leading to a quieter, and perhaps more private, living situation.
The components in insulated panels (including adhesives) meet some of the most stringent standards for indoor air quality, with low off-gassing. SIP panels have such low formaldehyde emission levels that they easily meet or are exempt from US Housing and Urban Development and California Air Resources Board (CARB) standards.
Architecture 2030’s mission is to rapidly transform the built environment from a major emitter of greenhouse gases to a central source of solutions to the climate crisis. For 20 years, the nonprofit has provided leadership and designed actions toward this shift and a healthy future for all. This article was written by Erin McDade and Lori Ferriss.
The latest reports from the Intergovernmental Panel on Climate Change (IPCC) are in, and the findings are clear: reusing and retrofitting our existing building stock is critical climate action. The Sixth Assessment Report names building reuse as one of the top strategies to mitigate climate change, stating that places with developed existing built environments will achieve “the largest GHG emissions savings by replacing, repurposing, or retrofitting the building stock.”
According to the IPCC, to have the best possible chance of meeting global climate targets, we must limit our remaining carbon budget to 340-400 gigatons of CO2 emissions. At a current average global emissions rate of approximately 40 gigatons per year, staying within this budget would require rapid decarbonization of every carbon-emitting sector, including the built environment, by 2040. This means achieving net zero across both operational emissions from using buildings and embodied emissions from constructing and maintaining them. Given such a short timeline, when assessing the best way to cut emissions in the building sector, we are compelled to think not just about how much carbon we reduce but when those reductions happen.
Pingtung Public Library by MAYU architects, Pingtung County, Taiwan Popular Choice, 10th Annual A+Awards, Architecture +Adaptive Reuse
While substantial new construction will be required to support a growing global population, and efforts are underway to deploy net zero operations and adopt low/zero embodied carbon materials and construction practices, most new buildings today come with a significant embodied carbon penalty as well as added operational emissions.
On the other hand, renovating an existing building typically saves 50% to 75% of the embodied carbon that would be emitted by constructing a similar new building, especially when the most carbon-intensive parts of the building, the structure and envelope, are reused. When coupled with critical operational decarbonization strategies such as improved energy efficiency, electrification, and on-/off-site renewable energy, building reuse represents the biggest bang for our carbon buck, especially in parts of the world with significant and/or underutilized existing building stocks.
Unfortunately, renovation rates lag behind IPCC-estimated requirements. Current global building stock renovation rates hover around 1% annually, but the IPCC estimates that decarbonizing the built environment in time to meet climate deadlines will require retrofit rates to increase to 2.5 to 5%, and perhaps as much as 10%, annually.
Pingtung Public Library by MAYU architects, Pingtung County, Taiwan Popular Choice, 10th Annual A+Awards, Architecture +Adaptive Reuse
The good news is that there are positive trends to accelerate building reuse on many fronts. To name a few: For the first time in the United States, AIA reported that architectural billings from reuse outpaced those from ground up construction. Funding opportunities are expanding from many sources, including the White House’s Inflation Reduction Act. The Pritzker Prize has recognized architects for exemplary stewardship of existing buildings in two of the past three years. David Chipperfield, this year’s laureate, states “Retrofit is not only the right thing to do, it’s the more interesting thing to do.”
Contributing to this trend is the expansion of tools and resources to support the planning, design and policymaking communities in assigning a value to the carbon-savings potential of building reuse. It has long been a truism in the building industry that “the greenest building is one that’s already built”, but despite this intuitive knowledge, the industry has lacked the ability to easily compare the variables of embodied and operating emissions over specific time frames for reuse and new-construction. This means that the potential avoided emissions associated with reuse are typically unaccounted for in design processes, owner requirements, and climate policies and regulations.
Pingtung Public Library by MAYU architects, Pingtung County, Taiwan Popular Choice, 10th Annual A+Awards, Architecture +Adaptive Reuse
Resources like the CARE Tool are paving the way for a significant uptake in building reuse as a climate solution. The tool, recently released by Architecture 2030, provides a user-friendly platform and easily accessible data to support key decision makers in understanding and quantifying the potential of building reuse to achieve dramatic carbon savings compared to demolition and reconstruction.
The benefits of reusing and improving existing buildings extend well beyond carbon reductions. For example, a strategic investment could leverage the millions of square feet of unoccupied or underutilized buildings to ease the record housing crises in the US and Europe. Investing in communities that have been subjected to historic discrimination in particular has the potential to bring equitable climate solutions that also have meaningful social and economic outcomes.
Carbon smart approaches to reuse will reduce habitat loss, deforestation and pollution, while strengthening neighborhood memory and identity, creating local jobs, building financial equity, increasing neighborhood resilience and empowering communities. The benefits are clear, and the time to act is now! Existing buildings are a key to a climate smart built environment. Let’s untap their potential to transform the existing built environment for a net zero future.
Pingtung Public Library by MAYU architects, Pingtung County, Taiwan Popular Choice, 10th Annual A+Awards, Architecture +Adaptive Reuse | Photo by Yu-Chen Chao
Erin McDade, Associate AIA, is Architecture 2030’s Senior Program Director. She leads the organization’s public policy and building reuse initiatives, focusing on developing data-driven solutions for building sector decarbonization.
Lori Ferriss, AIA, PE, is Goody Clancy’s Regenerative Renewal Practice Leader and Director of Sustainability and Climate Action, leading architecture projects and research investigations for premier educational institutions that are renewing heritage campuses while advancing climate action goals.
A Timber Revolution requires us to focus on reducing mass-timber structures’ raw-material use instead of trying to design the tallest possible wooden building, writes Maximilian Pramreiter.
The renaissance of wood as a building material continues and has major potential to support climate-friendly construction – but it must be used efficiently.
From the second half of the 19th century, almost every product in our lives changed from being made out of a bio-based material to a highly engineered fossil-based alternative. The materials used to construct our buildings changed from natural materials like wood, stone and clay – which were considered antiquated and inferior – to man-made materials like steel, cement and glass.
The renaissance of one of the oldest building materials – wood – has already begun
The combination of steel frames, formwork concrete and glass facades led to the emergence of skyscrapers and marks the beginning of the age of steel at the end of the 19th century. The ensuing race for the design of the world’s highest building reached its temporary climax in 2010 with the completion of the Burj Khalifa at a record height of 828 metres. Today, every well-known city has at least one famous skyscraper in its skyline and concrete, as well as steel, dominates the architectural landscape regardless of the size of the project or its structural necessity.
Much of the current discussion on climate protection therefore focuses on how to replace modern construction materials with climate-friendly alternatives. Against this background, the renaissance of one of the oldest building materials – wood – has already begun.
Wood has the ability not only to substitute carbon-intensive materials, but also store carbon in the built environment. This makes it the perfect climate-friendly building material and it is without question that wood will play a key role in transforming the global building sector into a carbon sink.
Quite naturally, a similar race to construct the highest timber building has started. Architecture publications are full of the newest, loftiest wooden skyscrapers, such as Ascent Tower in the USA, which is currently the tallest timber structure in the world at 87 metres, followed by the Mjøstårnet Building in Norway at 85 metres, the HoHo Tower in Austria at 84 metres and the Sara Kulturhus Centre in Sweden at 75 metres.
These innovative heights are achieved using a combination of concrete and engineered wood products, primarily cross laminated timber (CLT) and glued laminated timber (GLT). CLT especially has experienced rapid market growth, with production capacities doubling within a couple of years.
Both CLT and GLT have a distinct disadvantage: their raw-material footprint
Among other things, this success story is mainly driven by two factors. Firstly, engineered timber offers a high degree of homogenisation of the natural material wood, which simplifies structural design. Secondly, it provides the possibility to pre-fabricate complete wall and floor elements before delivery to the construction site, shortening overall construction times.
Nevertheless, both CLT and GLT have a distinct disadvantage: their raw-material footprint. It is estimated that roughly 2.5 metres-cubed of roundwood is needed in order to produce 1 metre-cubed of GLT or CLT, not counting cut-outs for windows and doors. The 1.5 metres-cubed of by-products generated are mainly used for low-value products like particle boards or burned. In comparison, timber-frame construction – which is only suitable for low-rise buildings – uses around 2 metres-cubed of roundwood per metre-cubed of timber-frame boards.
To use a real-world example, the aforementioned HoHo Tower is constructed using 365 metres-cubed of GLT and 1,600 metres-cubed of CLT. Based on our research, we estimate that around 4,100 metres-cubed of roundwood was needed to produce these materials.
So, should we stop using GLT and CLT? Quite clearly no. But we need to start thinking about how we can improve the material efficiency of GLT and CLT and whether we can use more resource-efficient wood products like laminated veneer lumber (LVL), laminated strand lumber (LSL) or oriented strand board (OSB) for some constructions.
The race to build the tallest mass-timber skyscraper is therefore missing the point over the longer term. The real race should be to build the mass-timber building with the smallest raw-material footprint.
Relying on a universal solution that can be applied to all projects, regardless of size, will not work and if the current path is followed thoughtlessly then history is going to repeat itself and society will not only have to deal with climate change, but also with severe resource shortages.
If the current path is followed thoughtlessly then history is going to repeat itself
To prevent that from coming to pass, we need to start using our wood more efficiently and to increase the proportion of material used in long-term products and constructions. As well as the raw-material footprint, the energy demand during production and the ability to reuse, repurpose or recycle the whole component or its constituents also needs to be considered.
At the same time, these challenges offer unprecedented architectural and designing possibilities. If we think about all the potential material combinations, as well as currently under-utilised wood species, the timber revolution offers a potential design versatility that is only surpassed by nature itself. It is not going to be a walk in the park, but pioneering never was.
This article is part of Dezeen’s Timber Revolution series, which explores the potential of mass timber and asks whether going back to wood as our primary construction material can lead the world to a more sustainable future.
