River Forest Passive House Designed in ArchiCAD Wins US Green Building Council Award
Northern Illinois’ first certified passive house has become a reality, thanks to the work of Tom Bassett-Dilley Architect, Ltd. The firm, led by Tom Bassett-Dilley, designed the home using ArchiCAD. As the first home to pass the strict certification process involved with Passive House standards, the home is also being recognized by the Illinois chapter of the US Green Building Council.
Including the finished basement the house measures 3,800 square feet. There is a detached, two-car garage. The home includes three upstairs bedrooms, an open living area plus in-law suite on the main level and a recreational room on the lower level.
The concept of a passive house; which originated in Germany, encompasses building and energy standards for living spaces. While constructing a passive house is a feat in itself, the Green Building Council award also recognizes the innovative strategies used in its creation.
Bassett-Dilley says the ArchiCAD model was where he tested out a variety of design choices, using the zone tool in ArchiCAD 16 to calculate treated floor area and volume and create custom documentation that was presented to the third party certifier – a must in Passive House certification.
“We used a parallel excel based energy model, PHPP, transferring area and window sizes as we went along. Putting our materials choices through excel based model served as a way to compare and see how the energy results relate. No model is perfect, but it is a good predictor for heating and cooling.”
Taking on such a strictly measured project as a passive house design, the firm was presented with a number of challenges during the design phase. One obstacle in particular – a big challenge in passive house design – was eliminating energy loss through the windows.
This was one area in which Bassett-Dilley says ArchiCAD worked to his advantage.
“In passive design, the windows and their shading are critical components of an accurate energy model. The windows we chose for this home were installed with exterior over – insulation. The way ArchiCAD let us model that, so we were able to show it with an over insulated frame on the exterior but not the interior – allowed us to draw it once, discuss installation with the builder, and take it into the PHPP to check it.”
Most of the windows are located on the house’s south side to maximize the collection of passive solar heat. Made by Zola European Windows, they are triple-paned, tilt/turn, inward-opening windows.
“We need to know how window energy is affected by various shading planes, whether adjacent wall, jamb, overhang, or neighboring building. When we’re modeling in ArchiCAD, we know precisely what those numbers are and how they will strongly influence the amount of energy you get or don’t get. The virtual building tool along with the climate data gives us confidence that we have created an accurate energy model.”
When it came time to choose materials for flooring, the owners made their selections based on durability, indoor air quality and low maintenance. Porcelain tiles grace the bathrooms and foyer, while upper floors have floors of bamboo. Cork covers the kitchen floor and the lower level of the home is covered in linoleum over foam insulation, concrete and vapor barrier sandwich to make sure the floor is waterproof and warm.
Bassett-Dilley became an ArchiCAD user circa 1999 on version 6 – making the leap from hand drawing straight to computer modeling. His firm creates a variety of buildings, residential and commercial – including new construction, remodeling and renovating as well as preserving historic homes and has found that 3D BIM fits well with his work. He’s also looking forward to the next version.
“I’m excited about ArchiCAD 17 and making use of the priority based connections. One thing I’ve learned in practice is that when you have a good model drawn from the detail level to the big picture, both documentation and construction are more efficient. We’re anxious to get going on that next level of modeling.”