Net Zero Near The River
A 70-structure campus at the top of the Mississippi has been in need of a serious retrofit. We join this major project in progress, studying not only the design selections but the tradeoffs and sacrifices along the way.
MASTER PLAN AND GOALS
- The building envelope will have a wall insulation value of approximately R60 and a roof value of approximately R70.
- All occupied spaces shall be provided with natural daylight.
- All occupied spaces shall have capability of natural ventilation, given the climate conditions of the site.
- The common lobby area and the lab corridor, known as the “sun corridor,” shall be minimally conditioned in winter and shall not be actively conditioned in summer.
- Ground source heat pumps shall be the source of winter heat/summer cooling. The system shall be designed to accommodate future expansion into the campus at large, and shall include an exterior vault sized to handle a future expanded geothermal well field for this purpose.
- Sensible heating and cooling shall be served by a radiant floor slab and zoned per major group occupancies.
- Ventilation shall be served by a DOAS, which shall deliver conditioned outdoor air to each occupied zone via displacement ventilation floor diffusers. The outdoor air flow rate is based on zone level CO2 sensors. The DOAS unit is provided with total (sensible and latent) energy recovery.
SOME TOUGH CHOICES
- Biomass as an onsite renewable
- LED lighting serving the whole building
- Digital lighting control
- Composting toilets
- Grey water
- Solar thermal for domestic water (instantaneous electric heat was selected)
- Mechanically controlled windows for natural ventilation mode of operation (see below for further discussion)
- Power monitoring/measurement