724 Ronalds St
Iowa City
High Performance
The student-built house at 724 Ronalds St in Iowa City had a goal of high performance in mind from the start. It not only was designed to help the city meet climate-related goals, it also had the big goal of becoming a net-zero house (net-zero refers to houses that generate as much energy as they use). With a combination of a deliberate design, sustainable products, and a high-quality insulation install, 724 Ronalds St truly is a one-of-a-kind high performance house.
Sustainable Products
Cellulose
The attic and exterior walls at 724 Ronalds St were insulated with cellulose. Cellulose is a type of insulation made from paper products, up to 85% of which are recycled. These products are often sourced locally- for example, from the newspaper you place in the bin each week. This local sourcing and reliance on recycled materials helps to keep other manufacturing input to a minimum, adding to cellulose’s sustainable nature. In addition, cellulose insulation has a low carbon footprint and a high amount of net carbon storage as compared to other insulation products, making it an easy choice for eco-conscious builders. While insulating walls with cellulose is not common because of cellulose’s tendency to settle after installation, Thermal Shop was thrilled to help meet all goals for 724 Ronalds St by completing a dense-pack installation, ensuring that the product won’t settle over time.
Mineral Wool
Interior walls at 724 Ronalds St were insulated for reduced sound transmission with mineral wood batt insulation. The mineral wool batts selected for this project were made from volcanic rock, with up to 70% recycled material (mineral wool itself is 100% recyclable). While mineral wool isn’t as green as cellulose, it definitely has some desirable features. For example, after an average of 200 days after installation, these products start to save more energy than was expended in order to make them. Because mineral wool is naturally fire-retardant, no extra chemicals are needed for this important safety feature. In addition, the rigid structure of mineral wool batts makes them settle very little, which means that their insulating, sound deadening, and fire-retarding capabilities hold up over long periods of time.
Efficiency
Another big goal for 724 Ronalds St was for it to be an energy-efficient house. This was desired not only to help Iowa City reach some of its climate goals, but to also make the student-built house more affordable for income-qualified renters; an efficient house simply costs less to run and maintain. Thermal Shop assisted in this goal by providing a high-quality insulation install. Deliberate attention was paid to air-sealing the property so conditioned air stays in and unconditioned air stays out, helping the house to not only maintain a stable year-round temperature, but to ensure a longer lifespan for the ductless mini-split system and the house itself. In addition, while code only requires a thermal barrier of R-49 in residential attics and R-20 in residential exterior walls, the 724 Ronalds St attic was insulated to R-60 and exterior walls to R-30+, ensuring an even more efficient house.
Efficiency was considered for every other aspect of the house as well. Water-efficient faucets were selected for bathrooms and the kitchen, energy-star windows and doors were installed, and even fans and other appliances were not overlooked: they are all energy-efficient.
HERS Rating
All of this energy-efficiency is objectively measured by something called a HERS Rating (Home Energy Ratings System)- which is the industry standard for measuring a home’s energy efficiency. Scores are given on a scale of 1-150, and the lower the score, the more efficient the home.
An average home built in 2006 has a HERS Ratings of about 100. At this point, 724 Ronalds St is projected to have a HERS score of 26- which is 74% more efficient than an average 2006 home.
LEED Certification
LEED is a certification for sustainable and energy-efficient houses. This certification, which is 3rd-party verified, considers building design, water and energy efficiency, materials, and air quality (among other factors) before certifying homes. LEED homes can use, on average, 20-30% less energy than other homes. 724 Ronalds St is anticipated to receive an LEED Gold Certification.
Surrounding Environment
An important goal for the student-built house at 724 Ronalds St was for it to “fit in” with the rest of the neighborhood. Ronalds St is part of a historic neighborhood in Iowa City and project planners desired that the house represent this designation. To that end, it was decided that the house could be no taller than two stories, and that its layout should resemble houses in the nearby vicinity. An interesting twist is that while the house looks historic, its modern building design makes it energy-efficient and sustainable.
