Creating Sustainable Construction Opportunities Using Virginia Wool

Commodities

Practices

Wool is a remarkable fiber, with many unique properties and a long history of use in human history. While clothing is often the first use that people think of, there are applications for wool in the construction, environmental protection and biomedical areas (Sun et al. 2023). One area of possible use for wool is the construction industry, where wool can be processed to serve as batt or loose-fill insulation inside of wall cavities.

Wool materials are composed of keratin and grow continuously from the animal. Wool characteristics depend upon several factors, including genetics, environmental stressors and management methods (Holman and Malau-Aduli 2011). Classification of wool is generally done by noting the thickness of wool strands, measured in microns (millionths of a meter) with smaller micron sizing representing finer grades of wool. The micron size of wool can vary from 40 microns to less than 17. Finer wools (typically less than 26 microns) are used for clothing products – especially those next to the skin – to prevent itchiness. Other fiber characteristics such as staple length (length of the wool fiber) are used to indicate how well the wool will spin and create yarn (Holman and Malau-Aduli 2011). Spinning fineness (SF) is another wool characteristic which is based on the standard deviation of the fiber diameter, where more uniform wool products (i.e. lower standard deviation) are better for spinning. These microscopic wool properties can be identified with an optical fiber diameter analysis (OFDA) tool, currently available at several facilities include Texas A&M University and Rensselaer Polytechnic Institute.

Several authors have studied wool insulation products (Sun et al. 2023, Dénes et al. 2022, Hegyi et al. 2021, Bosia et al. 2015, Korjenc et al. 2015, and Zach et al. 2012). Dénes et al. (2022) and Zach et al. (2012) both tested wool insulation for thermal resistance and found comparable values to similar insulation materials. Besides the thermal insulation potential, other traits of wool insulation have been studied:

• Low environmental impact of wool insulation versus synthetic products (Bosia et al. 2015, Korjenic et al. 2015, Zach et al. 2012)
• Improved air quality by reducing volatile organic compounds (VOCs) (Hegyi et al. 2021, Bosia et al. 2015)
• Reduction of indoor humidity (Hegyi et al. 2021)
• Improved sound absorption (Sun et al. 2023, Dénes et al. 2022, Bosia et al. 2015, Zach et al. 2012)
• Use of local materials, often identified as ‘regional materials’ in green building literature (Bosia et al. 2015)
• Use of a “bio-based material” and eligible to contribute to the overall bio-based material content of the building.

Besides research papers, there are practical applications of wool insulation currently in use. In the United States, there is one company, Havelock Wool (https://havelockwool.com/) in Reno, Nevada. Havelock Wool currently imports Merino wool from New Zealand to produce insulation products. Both batts and loose-fill insulation are produced. Batts are connected mats cut to fit between stud spacing in a building. Loose-fill insulation is blown into cavities and then covered with netting or gypsum wall board panels. Havelock specializes in building insulation, as well as van insulation products.

Insulation materials used in buildings are typically composed of woven or felted layers of material. The various fibers (fiberglass, rockwool, cellulose, wool, etc.) are woven together creating small air pockets in the material. The insulative value is dependent upon the size and number of these air pockets, which essentially contain small pockets of still air which prevent the transmission of heat through the material. Insulation is quantified by the term R-value, where greater R-value indicates better thermal resistance. The thermal resistance performance including R-value of insulation material can be measured by laboratories, such as Oak Ridge National Laboratory, NGC Testing Services or C-Therm Technologies, among others.

Typical fiberglass batt insulation has an R-value of 3.1 per inch of thickness (Owens Corning 2024). According to Havelock’s website, wool insulation batts have an R-value of 4.3 per inch, or 28% better thermal performance per inch. Havelock products also have a premium price, selling for $1.67 per square foot versus fiberglass insulation at $0.88 per square foot. Havelock wool batts have no formaldehyde or chemical bonding agents (Havelock 2024). Data is also provided for flame spread, smoke development, acoustics, water vapor transmission, fungi resistance, and flammability of materials (Havelock Wool 2024).

The processing of raw wool into wool insulation has several important steps (Corscadden et al. 2014). First, the wool must be scoured, or cleaned, to remove dirt, vegetable matter and lanolin. Next, the wool must be treated with a borate substance to prevent insects, mold, fungi and fire. If the wool is being processed into blown-in insulation, the wool is then sent through a picker to pull the fibers apart and individually “fluff” the fiber, creating the small air pockets described earlier. If the wool is being processed into a batt, the wool is sent into a carder and felter, which stratifies the wool fibers into long sections and overlaps the wool fibers to develop a uniform product. As with the loose-fill insulation, the batt remains fluffy maintaining air pockets needed to produce consistent insulation.

As was previously mentioned, Havelock sources Merino wool from New Zealand to produce their insulation products. This wool has a low fiber diameter and a high spinning fineness, which allows for the production of uniform products and promotes the cohesiveness of the batts. At the current time, there is little understanding of the range of fiber diameter and spinning fineness for the coarser Virginia wool that is being targeted in this study. So, while more consistent products have been produced, it is unclear how much change in fiber diameter and spinning fineness can be tolerated to produce a good insulation product.

Based upon the research and current production of Havelock Wool, our research team believes that wool insulation may be a viable product for Virginia wool. The purpose of this project is to explore the feasibility of producing insulation products using Virginia wool. To do this, we have assembled a faculty and farm team. Dr. Daniel Hindman is a Professional Engineer and specializes in the study of green building systems and construction of wood buildings. Dr. Tom Hammett is an expert in enterprise development and in the marketing of various sustainable biomaterial products, with previous experience in forest products, non-timber products, and regional tree syrups. He has managed two recently completed SARE funded projects. Dr. Scott Greiner is an Extension Specialist and focuses on the beef and sheep industries in the Commonwealth of Virginia. Daniel Banker is a sheep farmer who owns Whitegate Farms in Pearisburg, Virginia and is an architect at ZMM Architects and Engineers. Cecil King is a sheep farmer who owns Colonial Farms in Pulaski, Virginia and currently president of the New River Valley Sheep and Goat Association.

We believe there may be an opportunity to set up a regional or state collection and processing center to work with local builders and architects supplying regional building products. However, there are significant challenges to creating this industry. The local wool production must be large enough to consistently supply the demand of raw material needed. Payments to farmers for their wool would be commiserate with or potentially exceed the cost of shearing to offset this as a loss to the farm. There is need for more information on the challenges of cleaning, treating and processing wool. Finally, there must be a desire to purchase wool products from the building construction community at a price level which allows for a profitable industry.

The objectives of our study mirror these particular needs and attempt to answer the question of the feasibility of a wool insulation production facility. Objective 1 is to survey the current wool resources in Virginia. Objective 2 will explore the processing and manufacturing of wool insulation. Objective 3 will survey the opinions of local builders as to the viability of wool insulation as a product. Finally, Objective 4 will summarize recommendations from the previous objectives to guide the potential growth of a wool insulation facility.

Objective 1. Survey Wool Resources in Virginia – The purpose of this objective is to understand the amount of wool available throughout Virginia. Working with Virginia Cooperative Extension and the Virginia Sheep Producers Association (state sheep industry commodity organization), researchers will observe particular farms around the state to understand the scale of production. In particular, and with the help of our on-farm collaborators, we will observe shearing operations at their farms and collect samples of wool produced from shearing. At least six different shearing sites over the two-year project will be observed to understand the diversity and variability of the sheep industry. Samples of wool will be sent to test laboratories to determine the fiber diameter, spinning fineness and other qualities of the wool. Researchers will also observe wool pool operations in Virginia to gain an understanding of the process of selling wool and increase contact time with sheep farmers.

Because shearing is a seasonal operation, observations of shearing will be conducted during Summer 2025 and Summer 2026. Farm surveys will be sent out in Winter 2025 to estimate the quantity and capacity of wool flocks, breed of animal and purpose of the farm (meat, fiber, both).

Objective 2. Explore Manufacturing and Processing Needs for Wool Insulation – The purpose of this objective is to examine in detail the manufacturing needs for wool insulation. First, the researchers intend to travel to Havelock Wool to tour their facility and learn more about the process. Researchers will also visit local mills such as Shepherd’s Gate Fiber Mill in Franklin county, North Carolina to review the process of creating insulation and examine the larger scale equipment needed for processing. From a review of literature such as Corscadden et al. (2014), small-scale tools for scouring, picking, carding and felting of wool will be purchased. Using the wool supplied from Objective 1, small batches of insulation – both blown-in and batt – will be produced. The process will be tracked using a techno-economic analysis, including collecting data on time, energy used, and water needs. Also, the testing data of the wool will be compared with the final products generated for insulation. The process will also be overseen and reviewed by the project cooperating farmers. After the wool insulation samples are produced, these will be sent to a national laboratory for R-value testing to compare with results from Havelock Wool and other insulation materials.

Objective 3. Explore Marketing Needs and Building Construction Opinions of Needs – The purpose of this objective is to examine the marketing needs for wool insulation among the construction community and gauge the interest in using wool insulation by contractors. First, researchers will survey the Virginia residential construction building community as to their desires to use wool insulation in buildings. The survey will also explore if the respondents would be willing to pay a premium for regional green materials. Next, researchers will conduct in-depth interviews to demonstrate the insulation products to buildings and gain more understanding of how the insulation will be used.

Objective 4: Recommendations for wool insulation facility – The final objective of this project will produce a set of recommendations based on the potential to create a wool insulation facility. Researchers will present the final data to the project cooperating farmers, members of Virginia Cooperative Extension Service, Virginia Sheep Producers Association and the New River Valley Sheep and Goat Association. Recommendations will include:

• Is a local or regional processing facility for wool insulation or similar products feasible?
• If feasible, what are possible locations in Virginia
• Determine current price point for insulation products
• Determine current price point for wool purchases
• Estimated startup costs of facility