First Year HouseZero Performance
The first year of actual operation data included energy consumption and onsite energy production. Most building systems in HouseZero were commissioned in May 2020. The first full year of data (June 2020- May 2021) showed good results, although the building was not occupied during that time frame due to COVID-19. The final test for HouseZero’s performance will be completed after 24 months of uninterrupted, normal operation.
The ambition of the building is to reduce the need for delivered energy (electricity that leads to a high carbon footprint) to a minimum by utilizing thermal energy sources (e.g., a ground source heat pump and solar thermal panels) in combination with thermal mass and a low-energy system for heating and cooling.
The results from the first-year data: Total Energy Use Intensity (EUI) is approximately 54.1 kWh/m2 total energy. The EUI is 26.6 kWh/m2 without IT and plug load. As a lab operating 24/7, the building has a large IT load, which consumes 17.8 of the 54.1 kWh/m2 total energy (33%).
Advanced Energy Design Guides, led by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, proposed a target EUI of 73.2 kWh/m2/year for small to medium offices at 5A climate zone. Net Zero Annex (U.K.) and New Buildings Institute also provided two more aggressive targets, i.e., 55 kWh/m2/year and 56.8 kWh/m2/year, respectively. HouseZero currently meets these targets.
In terms of onsite energy production, the project aims to balance the carbon emissions relating to imported energy for operation (electricity) and the embodied emissions relating to materials, with the production of new renewable electricity exported to the grid. The production considered constraints, including:
- Available surface on the building with sufficient solar exposure, taking into consideration neighboring buildings.
- Positioning of PV panels in accordance with the original architectural expression in the area, which is protected by historical/preservation regulation.
The measured PV production for the first year is 38.7 kWh/m2 of the total area of the building, which is approximately 13% lower than anticipated as several disruptions due to testing happened during the first year. Utility meters versus building electrical energy consumption is used to estimate PV production. The PV system was partially functioning from September 1 to 24, 2020; January 20 to February 12, 2021; and May 7 to May 29, 2021, due to setting experimentations on the batteries side. In addition, it was found that there have been uncertainties in PV harvest measurements with the existing PV metering systems and possible system efficiency loss. Inverters are identified as a possible source of inefficiency. At the end of August 2021, a new meter was installed to record the PV harvest that can be utilized by the building or exported to the grid, which will allow for cross-validations and a higher degree of PV harvest reporting.
Based on data from the first operational year (June 2020-May 2021), HouseZero demonstrates that surplus onsite renewable energy generation can offset emissions associated with the primary building structure (which does not include emissions from technical equipment), provided that the photovoltaic (PV) production can achieve optimal efficiency as designed, and the building performance is maintained. Using existing standards, calculations were conducted by the CGBC based on total load without IT (e.g., data servers) and plug loads and the interpolation of some unavailable data.
Read the full publication, “Comprehensive assessment of operational performance of coupled natural ventilation and thermally active building system via an extensive sensor network” in Energy and Buildings.