CASE STUDY | THE HOUSE AT CORNELL TECH In addition to the PHPP model not predicting actual use, there were some addressable reasons for the higher actual energy use compared with what was anticipated. One issue was the behaviour of the systems and residents. For example, in winter when the outside temperature drops below freezing residents entering their apartment chilled from being outside may be inclined to turn up the heat to full immediately, rather than waiting to acclimatise to the internal environment. There were likely situations where there was more heat used than there needed to be, so a cultural shift had to happen, Janiski says. The buildings residents are primarily one-year Masters students, so the occupants typically change from one academic year to the next. To introduce Passivhaus living and explain how the buildings operation differs from accommodation students are likely to have experienced, the university has created a residents guide. This includes information about Passivhaus certification and the intended operations of the heating and cooling systems. The building also features an energy dashboard in the lobby, where all residents can see the actual energy use and how they compare. The energy used during the shoulder seasons for heating and cooling has been flagged as an opportunity for improved operational efficiency. The modelling methodology in the PHPP also presents a number of significant differences from the local ASHRAE 90.1 modelling methodology, as well as any approaches that seek to predict actual use. For example, the PHPP methodology assumes that, when the temperature and humidity are nice outside, occupants will open their windows and turn heating/cooling systems off. This action not only needs a cultural shift to rely less on active heating and cooling, it also requires that residents turn off the system when their windows are open, which is acoustically comfortable given that the building is adjacent to the Queensboro Bridge. The multi-tenanted aspect of the project, which meant the building incorporated amenities such as a gym, yoga room, and a laundry room, were also cited as being outside the traditional family home PHPP model, which, Janiski says, all add up. The common area electricity, and high plug loads serving a technology-driven The House at Cornell is situated next to the Queensboro Bridge resident population, are noted areas of opportunity to find additional efficiencies. The project team has been working with the owner to review detailed building operations data related to equipment, ranging from the heating and cooling VRF system to the elevators, to evaluate further optimisations. The ambition of the scheme in implementing Passivhaus at this scale was recognised by the judges at this years CIBSE Building Performance Awards where it won the Project of the Year Public Use category. They praised the Buro Happold team for its holistic integration of engineering, social aspects and lessons learned. Janiski says its an honour to have awards, but the most meaningful part of this experience is that our impact stretches from the scale of the individual occupants improved health to the scale of cities through the advancement of energy codes and GHG emissions reductions. Lastly, she underscores the importance of the team working together, and her gratitude for having such clear vision and leadership from the project developers and university. CJ See details of all the 2021 Building Performance Award winners at cibse.org/bpa 22 April 2021 www.cibsejournal.com CIBSE April 21 pp18-22 House at Cornell Tech.indd 22 26/03/2021 17:27