Dartmouth College’s Dana Hall uses four highly effective strategies to reduce the building’s energy footprint within a tight construction budget. The renovation reuses the concrete and steel structure of the original 1962 library building, implements highly insulating walls and roof, makes use of ultra-high-performance glazing and incorporates a photovoltaic shading canopy to reduce predicted energy use by 90% compared to baseline.
The design strategically adds an addition at the south of the existing structure to create an arcade at the ground floor with shared spaces above. The reuse of existing structure reduced the amount of new high embodied energy materials like steel and concrete used in construction.
Insulation is a tremendously cost-effective energy efficiency measure. Supporting a light terracotta facade, the lightweight stud walls combine 6″ of continuous exterior insulation with 5 1/2″ of cavity insulation to provide an effective R-30 wall value, twice the code minimum. The roof system provides a minimum R-60 continuous insulation, triple the code minimum.
The glazing strategy for Dana Hall combines careful proportions, locations, recesses, canopies and topography with advanced technologies. The triple-glazed punched windows on three siddes of the building are tall and set deep in the wall with two low-E coatings to minimize heat gain. Continuous curtainwall glazing at the ground floor is under cover from the floor above. The penthouse is shaded by the photovoltaic canopy.
The new south addition is clad in an advanced all glass facade system designed with passive measures and active controls to produce a thermally efficient envelope responsive to its environment. The glass facade is made of 2″ triple-glazed insulated units and high-performance vacuum insulated glass panels arranged in response to orientation and to maintenance of visual connections to the landscape beyond. Both units have integral expanded metal mesh shading and are silicone structurally glazed to a thermally-improved aluminum curtainwall frame. Each component is optimized for thermal performance with a whole system R-value>8, more than four times more efficient than the latest energy code requirement. The system also pairs automated vent windows with daylight-responsive shades to allow simultaneous daylight control and natural ventilation.
The small penthouse at the roof of the existing building allow for a terrace roof garden with a solar canopy above. Covering nearly the full existing roof area, the 68kw photovoltaic panel canopy reduces the building’s predicted energy use index (pEUI) from 25 to 15 kBtu/sf/yr.