The career demands of a young married couple dictated finding a suitable city residence, one that had plenty of space and was located close to downtown Chicago. With a shorter commute, the parents would be able to spend more family time with their two children. Knowing that they planned to live there for at least 15 to 20 years, the owners recognized early in the process that they wanted the home to have energy efficiency, quality, and permanence. They determined insulating concrete form (ICF) walls provided the best performance for their needs.
The owners realized that it was important to get certain items, like the exterior envelope, done right the first time. It would be difficult to replace or modify these later. But features like kitchen cabinets, floor finishes, or countertops, could be upgraded as budgets permitted.
They investigated various options for how best to build. They selected ICFs for the quality, speed of construction, and high performance that could be realized, such as energy efficiency that would pay back year after year. Thick continuous thermal insulation and solid concrete would reduce air infiltration more than conventional construction would allow. High performance windows were also chosen to complete the envelope and maintain good energy efficiency. The structural strength of concrete would keep their family safer.
Project architects designed the 4,100-square-foot, four-story home to achieve a silver rating under the LEED® for Homes green rating system. Construction took ten months, with the exterior walls stacked and placed at a rate of about one and a half weeks per floor. It was the first time the general contractor had built with insulating concrete forms, so the ICF manufacturer provided onsite training. The contractor felt this greatly reduced the learning curve and sped construction.
Beyond the envelope with ICFs and quality windows, owners chose additional features to enhance environmental performance to make this home green and sustainable:
- Insulated basement floors with radiant heat, finished by staining and sealing.
- A geothermal heating system consisting of nine wells, each run vertically to a depth of 90 feet.
- Solar heated domestic water system which also supplements the geothermal heating system.
- A green roof consisting of plants in removable trays qualifying for a $5,000 city grant.
- Exterior finished with fiber cement wall panels
- Low volatile organic compound (VOC) paints.
Stairs serving all levels of the home are located along one side of the plan from basement to roof. The stairway is open to all floors and capped with a small penthouse structure with operable windows. This multistory space works like a chimney, creating a stack effect to draw air up and through the entire home. Little need for air conditioning is anticipated in the summer with the combination of the well insulated ICF walls and the natural ventilation provided by the stairway.
Although the design made energy sense, the owner wanted something tangible to prove it. So, to quantify performance, a home energy rater was employed; reviewing plans, conducting field inspections during construction, and even testing and rating the home. While most homeowners are unlikely to make this kind of effort, this family wanted to know what they achieved. The end result was very satisfying: the house obtained a Home Energy Rating (HERS) energy rating of 41, meaning it will perform 59 percent better than the mandatory minimum energy code requirements for all new homes built today. That represents exceptional efficiency, particularly in a colder climate like Chicago, and was well worth the money spent.
The family took up residence in 2010 and is pleased with the performance and operating cost savings of their concrete home. With the important basics covered, they can now turn their attention to more important things, like spending quality family time together.