Why Not Wood? (Mass-Timber Construction)

Jason Norman (Building Construction Technology) ; Miranda D’Oleo (Environmental Science) ; Liya Woldemariam (Envi. Sci.) ; Dylan Haley (Natural Resource Conservation)

 

The building sector releases greenhouse gas emissions that contribute to climate change and could have a significant impact on the people and town of Amherst. The carbon dioxide that is emitted into the atmosphere has the ability to trap and store heat near the earth’s surface through the greenhouse effect. Just over the past century, there has already been a 2°F increase in temperature in the Commonwealth (Environmental Protection Agency, n.d, p.2). This has raised concerns regarding the damages that will result from the increase in temperature on human health. It is projected that there will be a 50% increase in the number of heat related deaths, increase in asthma and accelerated spread of diseases through pests (Town of Amherst Energy Conservation Task Force, n.d,  p.10). An increase in temperature and precipitation along with the increase of pollution have shown to increase the incidence of asthma. Pollutants such as smog are expected to increase with high temperatures. These pollutants have been linked to cause respiratory issue (EPA, n.d). Also, high temperatures lead to increased spread of diseases through insects. Insects such as ticks that transmit lyme disease function best in temperatures above 45°F. This means that as winters become warmer the length of time that the ticks are present increase (EPA, n.d). All of these risk and consequences to human well-being and health are too high to not implement policies, in the building sector specifically, meant to mitigate against climate change.

In order to make construction more sustainable, there needs to be a shift in modern building materials to wood to make building construction more environmentally and energy conscious. When looking at low rise commercial buildings, wood materials have the capability of providing a more sustainable alternative to more conventional building materials such as concrete. The lumber industry has made great strides in energy efficiency, with 76% of manufacturing energy for lumber coming from residual wood, producing self-sufficient energy (Bowyer, 2012). To meet the growing needs of housing in Amherst while also mitigating the the adverse effects of climate change, we propose the town of Amherst adopt an ordinance to mandate all new commercial low-rises use wood as a structural (Load bearing) construction material. This practice is also known as Mass timber construction. In tandem with this, we propose the current height limit for commercial wood buildings be increased from its current value of six stories, to allow for further adoption of timber materials in the construction of commercial residential buildings in the town of Amherst. For the purposes of this paper, we use Emporis’ (A global building information provider) standard ESN 49213 to define a low-rise, “an enclosed structure below 35 metres [115 feet] which is divided into regular floor levels” (Emporis,2009).

The town of Amherst is home to three of the five college consortium including Amherst College, Hampshire College, and the University of Massachusetts Amherst (UMass). Due to the presence of these universities, the town of Amherst is unfortunately suffering a housing shortage (RKG Associates, 2015, p.2). These institutions pose major pressure on the housing market in Amherst. Together these institutions demand for more off-campus housing, especially for UMass.  UMass only provides housing for 61% of its 23,515 undergraduate student population (RKG Associates, 2015, p.2). Thus, this leaves over 10,000 students that are looking for off-campus housing. In addition there are 7,078 graduate students and over 1300 full time instructional faculty members looking for housing near the university (UMass at a Glance). The high demand for housing by students and faculty has substantially impacted the availability of low-moderately priced housing for low-income families. Students looking for off campus housing have priced out low income households with their ability to rent out per-bedroom as opposed to the whole entire rental unit. Most students are paying for the monthly rent per bedroom, so the aggregate monthly rent of all the individual renters comes out to be greater than what a household earning 30,000-40,000 can afford (RKG Associates, 2015, p.4).  

In the Amherst Housing Market Study conducted by RKG Associates, they discovered that there is a limited range in housing prices, which disadvantages these low income renters. In addition, student renters tend to out spend non-student renters, adding to the housing pressure low-income renters feel. They attributed this occurrence to regulations imposed by the town that limit development density and type. The high demand and low supply of rental units has incentivised the development of high end luxury apartments as they have a higher return on investment. An example of this is the commercial residential building One East Pleasant built in 2018. This apartment complex located in the heart of downtown amherst is priced at $2,590 to $2,990 a month for a 2 bedroom unit. This has resulted in limited low to moderate priced homes as developers are incentives to build luxury apartments that are more profitable.

In order to meet the growing needs of housing for a growing population and low-income families, Amherst will need to expand its residential capacity in the near future. The number of residents here has been steadily growing in past years, the town as a whole grew by five and a half percent between the years of 2010 and 2017, which is almost two percent higher than the state average (“Amherst, Massachusetts Demographic Data” (2018)). Some areas, like South Amherst, have seen a growth of 8.5% over the same period. The town is already working on more housing development to compensate, like the 130 mixed residential units being constructed in North Amherst (Whitlow, 2017).

While the town of Amherst is in need for more housing, not all of its residents are on board for making these changes. This movement for blocking of development is popular enough to warrant a platform in the local political scene, like town council candidate Darcy DuMont. In her public letter, she vocalizes the concerns of citizens who dislike the current trajectory of Amherst’s development because of its clash with current architecture (DuMont, 2018). The look of any new construction is among the most influential to many locals, and plenty of backlash could be expected unless this aspect is also considered moving forward. These people don’t want the image of their quaint farming town to be disturbed by excessive housing development, which is further backed by Neumann’s article that mentions voiced concerns over new building changing character of the town, as well as not being green enough (Neumann, 2018). Therefore, the issue that we’re resolving isn’t only increasing the town’s residential availability in a way that’s sustainable with respect to cost and environmental impact, but also in a way that won’t drastically harm the small town aesthetic that many here value greatly. We also see this current construction trend as an opportune entry point for our policies mandating the incorporation of timber products in the building sector.

Amherst is at the forefront for sustainable practices and have the backing from the town and its people who support the protection of the environment. Through the voting at a town council meeting on November 8, 2017, the people have committed that all new municipal buildings and additions costings over one million dollars be zero energy, net zero (Zero Energy Amherst, 2017). A zero energy building (ZEB) generates renewable energy that satisfies its annual energy consumption and replaces the nonrenewable energy that is used in the building sector.  (U.S. Department of Energy, 2015 ). This leads us to believe that there will be support for this initiative as it will help the town accomplish this building standard for the future development of these residential buildings, using wood materials will allow this goal be easily met. In order to meet the zero energy building code in Amherst, the building sector must lessen the use of conventional materials in low-rise commercial building construction and thus shift to wood materials that will help decrease the greenhouse gas emissions in the building sector.

Current construction processes are non-sustainable and carbon and energy intensive, and contributes to climate change. Construction contributes to climate change by releasing a large amount of carbon dioxide (CO2) into the atmosphere, estimated to be at about 39% currently. (Global Status Report, 2017).  If we can find any way to make construction greener then we can reduce the amount of greenhouse gases that are being emitted during production, transportation, and construction.

Fortunately, the problems of construction contributing to climate change can be mitigated if the building sector shifts their use of conventional materials to wood materials. The use of wood materials instead of conventional materials for building construction can dramatically reduce greenhouse gas emissions and be a solution to this problem. Any change in building practices towards greener materials and methods will improve our chances against climate change significantly. Many advancements have been made and studies have shown that Cross Laminated Timber is a substantial building material that meets structural requirements of a building and utilize less CO2 in the construction of the building (Holt, 2017). A comparison study looked at wood and cement and glass wool buildings  and found that the wood buildings release less than one-fifth of the greenhouse gas emissions of cement and glass wool buildings. The wood building released 82.1% fewer kilograms of CO2 than the cement and glass wool building (Bhochhibhoya et al., 2017, p. 51). Based of this study, there should be a transition to wood building materials in order to decrease CO2 emitted from the building sector that contribute to climate change and used to make a zero energy building.

One of the underlying causes of energy intensive construction industry is the wide use of concrete materials in the construction industry. The cement industry alone is the most  energy-intensive of all manufacturing industries (U.S. Energy Information Administration, 2013). Concrete production is a highly energy intensive process due to the chemical process of making cement, which is major component of concrete manufacturing. Cement production emits high levels of CO2. The CO2 is produced during two the stages of cement production, the first is through the fossil fuel energy used to run the cement making process and the second being the decomposition of calcium carbonate during the process of making cement. Through the concrete production process, 30% of CO2 comes from the energy required to drive this process (bringing massive furnaces to high temperatures) and the other 70% comes from decarbonation (the process of limestone releasing carbon dioxide and becoming lime) (Green Specs). Concrete results in the emission of CO2 in all the stages of its production which contributes to the construction sectors significant impact on the climate. Unlike more sustainable materials like wood, concrete is easily accessible as most of the resources necessary to create this building material are more widely found. As for the cost, concrete is often the more affordable option due to the easy sourcing, and there aren’t any stringent policies which would attach a cost to the emitted CO2. Concrete is also often valued more highly due to perceived durability and fire-safety (“Precast Concrete vs. Steel Framing vs. Wood Framing”, 2018).

Another reason for the use of concrete building materials is the social bias and perception of the durability of the material (March, 2017).

There is a stigma associated with more sustainable timber building materials because of people have reservations about the flammability of wood materials (Busta,2017).

When we examine energy demands, we cannot focus on only one part of a materials life, we must take into account the demands during production, manufacturing, transportation, and lifespan, a concept known as embodied energy; the different construction materials have different embodied energies. The conclusion is that construction that involves wood materials have less embodied energy than traditional materials such as concrete (Svajlenka et al., 2018). In central Europe, modern construction systems based on wood showed a 54% reduction in embodied energy than traditional masonry construction methods such as concrete (Svajlenka et al., 2018, p. 8).  This is due to the fact that the majority of the energy used for wood materials is mainly contributed to the transportation of the material while concrete materials are energy intensive in the production and manufacturing of the material (source).

Replacing these unsustainable materials such as concrete, brick, stone, steel and glass facades with environmentally responsible wood exteriors will provide the homier appearance that critics of new construction want. The appeal of the appearance of wooden construction is expressed effectively by NBS, “Timber is a material with a unique charisma – it was, after all, once living, and its organic origins are clear in its appearance and texture. It also has an historic resonance, since a thousand-year tradition is still evident in the great frames and roofs of the medieval period and earlier” (Ross, 2009, para. 1), which is why it fits so well for what the town seeks to emulate. The close alignment of the ageing and authentic with most resident’s desires is why it seems that wooden structures would help satisfy the intense set of standards our housing solution will be put up to. In fact, the town of Amherst has been happy to broadcast that they’ve implemented wood construction already; the John W. Olver Design Building is praised because of the building’s ingenuity and forward thinking. Local reports, like from the Hampshire Gazette (Castillo, 2018) finds appeal in this project in almost every detail, even the smell. As Castillo put it, just being inside the building gives an uplifting impact that “you just don’t… with steel” (Castillo, 2018, para. 3) and this is why the town will be more accepting of wood than modern construction materials to keep Amherst feeling like home. UMass is proud of the Olver Design Building because they understand how good projects like this make them look to others, and the town as a whole can capitalize on being at the forefront of wooden building innovation.  Building more residences in this town isn’t much of a choice, and so they might as well be designed in a way that most appeals to those who will be looking at them.

Moving forward with our proposal, we acknowledge a potential for backlash from the construction contractors who would have to deal with these material changes first hand. Because of fears regarding change of practices, a possible jump in price of materials from conventional building materials to wood, or doubts regarding durability. However, it seems as though economic concerns may be a bit misleading and less relevant after first glance. A study done by Home Building Smart found that after considering the costs of both materials and labor, home construction between different materials is very similar in price “Home Building Materials Cost” (n.d.). In fact, in a case-study between concrete/steel and Mass Timber (wood frame, CLT walls/roof) designs for a performing arts building, the cost per square foot was lower for both Green options than the standard concrete/steel design. Laguarda-Mallo, Maria & Espinoza, Omar. (2016).  On the other hand, by enticing potential residents with homes that are more appealing because of their wood component, the number of people interested in local housing will rise. Not only will those in the housing market be drawn to the wood aesthetic, the main reason cited for Mass-Timber over light-frame construction on the T3 building in Minneapolis (Busta,2017). The decreased construction time is another incentive, shortening the move-in waiting period because many wood frame buildings, both residential and commercial, can be pre-fabricated (or partially built elsewhere), (“The Enduring Popularity of Wood Houses,” n.d.). By increasing housing interest, more possible projects will be available for the contactors and allowing for their income to be more secure.

It is clear that the construction sector is having an adverse effect on our environment, and yet must be continued to meet the needs of Amherst’s growing population. Our goal is to reduce the impacts that our local construction has on the environment by decreasing the greenhouse gas emissions while keeping the local residents as satisfied as we can with the changes that the town must undergo to more housing for students and low-income families. Moving forward with policies that the town has already implicated in hopes to lessen their emissions, we encourage the use of timber products in these projects, new commercial buildings, seems to be a great way to achieve this. Proposing the town to adopt a legislation to have all new low-rise commercial buildings to use wood as a structural (load bearing) construction material and increasing the height limit for commercial wood buildings from its current height of six stories. This will allow for more use of timber materials in commercial residential buildings in the town of Amherst. Through the implementation of this new policy of the incorporation of timber products and the reduction of the use of conventional materials in future construction, we believe that a substantial change, a decrease, in the amount of greenhouse emissions will be possible in the town of Amherst. Hopefully this policy will be able to meet the needs of all important parties involved and affected in this matter, consisting of the town council of Amherst, Massachusetts and the Energy Climate Action Committee, the town residents, and the contractors who would be carrying out these plans. If successful, then we see a future in which Amherst can expand its population while mitigating environmental impact, as well as keeping any one group of its population from losing too much in the process.

References

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Bhochhibhoya, S., Zanetti, M., Pierobon, F., Gatto, P., Maskey, R. K., & Cavalli, R. (2017). The global warming potential of building materials: An application of life cycle analysis in nepal. Mountain Research & Development, 37(1), 47-55. doi:10.1659/MRD-JOURNAL-D-15-00043.1

Bowyer, J., PHD. (2012). Utilization of  Harvested Wood by North American. Product Industry. Dovetail Partners Inc., 1-22. doi:http://www.dovetailinc.org/report_pdfs/2012/dovetailwoodutilization1012.pdf

Castillo, A. (2018, June 14). UMass multi-level building showcases cutting edge timber construction. Daily Hampshire Gazette. Retrieved from https://www.gazettenet.com/UMass-building-construction-18113631

DuMont, D. (2018). Darcy DuMont: ‘Hit the pause button on additional buildings’. Daily Hampshire Gazette. Retrieved from https://www.gazettenet.com/Dumont-letter-20454796

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Neumann, J. (2018). Columnist Johanna Neumann: Building resilient communities. Daily Hampshire Gazette. Retrieved from https://www.gazettenet.com/Neumann-column-20243579

Precast Concrete vs. Steel Framing vs. Wood Framing. (2018, October 03). Retrieved from https://nitterhouseconcrete.com/precast/concrete-cost-vs-steel-and-wood/

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U.S Energy Information Administration (2013, July 1). The cement industry is the most energy intensive of all manufacturing industries. Retrieved April 11, 2019, from https://www.eia.gov/todayinenergy/detail.php?id=11911

Whitlow, T. (2017, December 20). Mixed housing development coming to Amherst. WWLP. Retrieved from https://www.wwlp.com/news/local-news/hampshire-county/130-affordable-housing-units-to-be-built-in-amherst_20180327074407288/1082376252

Zero Building Energy and Communities. (2017). Zero Energy Amherst. Retrieved from https://zeroenergyamherst.weebly.com/

Laguarda-Mallo, Maria & Espinoza, Omar. (2016). CROSS-LAMINATED TIMBER VS. CONCRETE/STEEL: COST COMPARISON USING A CASE STUDY. World Conference on Timber Engineering, At Vienna,Austria

doi:https://www.researchgate.net/publication/320739097_CROSS-LAMINATED_TIMBER_VS_CONCRETESTEEL_COST_COMPARISON_USING_A_CASE_STUDY

  • Cost comparison shows green options cheaper than concrete/steel | Survey shows primary factor in materials selection for builders is cost compared to alternatives

Holt, Rebecca. “Mass Timber: Tall Wood Buildings for High-Performance Design (USGBC Northern California).” U.S. Green Building Council, 2017, www.usgbc.org/articles/mass-timber-tall-wood-buildings-highperformance-design-usgbc-northern-california.

March, Mary Tyler. “UMass Opens Largest Engineered Wood Building in Northeast US.” Construction Dive, 26 Apr. 2017, www.constructiondive.com/news/umass-opens-largest-engineered-wood-building-in-northeast-us/441249/.

Busta, Hallie. “Mass Timber 101: Understanding the Emerging Building Type.” Construction Dive, 24 May 2017, www.constructiondive.com/news/mass-timber-101-understanding-the-emerging-building-type/443476/.

https://www.amherstma.gov/242/Socioeconomic-Data

“Low-rise Building.” EMPORIS, www.emporis.com/building/standard/15/low-rise-building.

jnorman

2 Comments

  1. Interesting article! My initial thought was much like everyone else’s when I jump to thinking about the flammability. Glad to see you covered that in the article, seems to make a lot of sense. As a deck builder myself that loves working with natural wood I think it is an awesome idea!

  2. I believe that using wood to make building construction more environmentally and energy conscious would be a great choice and by supporting environmental activist.

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