In early Spring, 2004, the partners at Locus met to discuss the goals for Red Square, our new office building in NE Minneapolis. Although we expected some eventual push-back on our aesthetic goals (i.e. the fire engine red siding), we didn’t expect to run into a roadblock from city officials on our sustainable approach. This is especially true since the City of Minneapolis has adopted the goal of promoting sustainable development in their comprehensive plan. Midway through our approval process, we ran into a roadblock as zoning officials denied approval for an integral part of our sustainable design, the insulating Thermal Doors on the south facade.
Why Are The Red Square Thermal Doors Sustainable?
The power of the sun is significant and free. In our climate, at our latitude, we need to manage the use of this since there are times, i.e. the winter, when we want to absorb as much of the energy as possible and other times, i.e. the summer, when we need to shield ourselves from it. Our design for the south façade of Red Square takes full advantage of the sun’s power when needed and shades the building from it when it produces adverse conditions.
During the winter, south-facing glass loses more than 150% of the energy it takes in through heat gain. With our insulating doors, however, we reverse this to be a net gain of energy by taking in the energy during the day through the unobstructed glass and covering the windows at night when the thermal doors are down. For our building, this savings is equivalent to 8,400 lbs. of CO2 not being released into the atmosphere and the work of 175 mature trees.
During the summer months, the reverse is also true as the doors shade the windows, keeping the summer heat outside. When the doors are in the open position (24 hours a day from April through October), the windows on the south façade of Red Square are shaded as the sun moves through the sky at a very high angle. This eliminates most of the detrimental heat gain produced by the sun at this time of year.
Although we eventually secured approval for the doors, the extended process consumed precious additional time. We were also required to add windows elsewhere in the project that diminished the impact of the thermal doors. If we as a community are going to be serious about making buildings that are more environmentally benign, we’ll have to understand that they may look and operate differently.