The Passivhaus standard for building energy efficiency is gaining interest in North America as an alternative green building standard. In Canada, the first Passivhaus projects have been residential projects, perhaps prompted by the English translation of the original German as “Passive House.”
However, the adoption of the Passivhaus standard for non-residential building in other jurisdictions has found that it enriches the design process and adds value to completed buildings. As such Passivhaus has much, and possibly more, to offer owners, authorities and consultants in British Columbia.
As a performance-based rather than a prescriptive or ‘tick box’ approach to low energy building design, Passivhaus offers designers considerable freedom. Performance is achieved with an ‘envelope first’ approach to design that allows simplification of other building systems.
Key targets include: a low space heating energy demand of less than 15kWh/m2 of floor space per annum; a low source energy use intensity (EUI) combining heating, cooling, hot water and electric consumption of less than 120 kWh/m2 per annum and a highly air tight building delivering less than 0.6 air changes per hour.
These performance targets, when compared to an academic or small commercial building designed to current Building Code (2014), suggest that energy savings of more than 50 per cent are achievable. This dramatic reduction in energy consumption has been achieved in many evaluation projects and more than 50,000 Passivhaus units have been built globally in the past 20 years.
Passivhaus has been found suitable and able to deliver the same levels of energy performance, regardless of climate, for many building typologies from swimming pools to supermarkets and refurbishments to multi-family residential. In particular, a number of school and academic projects have successfully met the Passivhaus standard where post occupancy evaluation has validated the designed energy performance and identified additional benefits, including good indoor air quality and daylighting.
Lessons learned from the design and construction of these buildings are readily available and disseminated by the Passivhaus community. The proven energy performance of Passivhaus has much to offer Part 3 Building Code projects in British Columbia.
As different levels of government explore new ways of implementing policies to combat climate change, Passivhaus is well placed to deliver. The performance-based approach is aligned with emerging innovations in development policy that look to control building energy performance in terms of source EUI rather than any one overarching energy standard.
Existing energy assessment methodologies, often using financial energy cost savings relative to a hypothetical baseline building, do not always deliver policy objectives. As Passivhaus already targets a source EUI target of less than 120 kWh/m2.a, it seamlessly interfaces with a restricted energy consumption, or energy density, approach to development policy.
The dramatic energy savings of Passivhaus complements existing green building standards. For example, a Passivhaus design may contribute at least 20 points to any LEED project in terms of energy consumption and indoor environmental quality alone. The extremely low energy demand also facilitates the installation of on-site renewable energy sources to tip buildings into net zero or even net positive levels of performance.
New Passivhaus ‘Plus’ and ‘Premium’ standards have recently been announced to support these levels of carbon emission performance. This is of particular importance for public sector buildings that make carbon offset payments to meet net zero emission legislation. Economic benefits of low consumption will also become increasingly important as local energy costs start to rise.
If a building is designed to consume 50 per cent less than a comparable current code building, the projected BC Hydro rate increases of 15 per cent in the next two years and possibly 45 per cent in the next 10 years will be mitigated considerably. Appropriate design solutions implemented today will continue to offer value into the future.
Many jurisdictions have experienced a steep learning curve to implement public sector and commercial Passivhaus projects. However, unlike other jurisdictions, British Columbia in recent history has established a body of existing architectural and engineering building envelope professionals that are well aware of local industry, climate and technical constraints.
The application of this unique knowledge base can support the delivery of Passivhaus projects in British Columbia to achieve superior energy performance, lower long term operating costs while meeting emerging development policy objectives at minimal extra cost.
Adam James RIBA is a Certified Passivhaus Designer and UK Registered Architect working at Acton Ostry Architects. Further information on the Passivhaus standard can be found at www.passivehouse-international.org/upload/ipha-brochure/
