Net zero carbon. Passive House. These two terms have been of much discussion in the world of building design and are now becoming more enticing to the eco-conscious public. But what does it all mean, and are such goals Utopian or achievable?
To achieve a net-zero carbon building, the amount of emissions released by the building on an annual basis must be zero or negative. Building design strategies and energy initiatives such as the implementation of renewable sources all play a part in determining if a building can achieve this status.
While Passive House is the term commonly used, this standard applies to both residential and commercial buildings. The design standard refers to a rigorous set of principles used to attain a quantifiable level of energy efficiency. According to Passive House Institute U.S. (PHIUS), passive house building is designed and built around these five principles:
- Employs continuous insulation throughout its entire envelope without any thermal bridging.
- The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air.
- Employs high-performance windows (double or triple-paned windows depending on climate and building type) and doors – solar gain is managed to exploit the sun’s energy for heating purposes in the heating season and to minimize overheating during the cooling season.
- Uses some form of balanced heat- and moisture-recovery ventilation.
- Uses a minimal space conditioning system.
Per Minimizing Heat Flow: Using Air Barriers and Continuous Insulation to Meet Passive Design Standards in Walls & Ceilings magazine:
One key way to achieve these rigorous standards is to incorporate state-of-the-art continuous insulation wall systems and air moisture barriers into the design. These alone can dramatically reduce consumption, reducing a building’s carbon footprint compared to that of buildings with non-insulated brick or stucco cladding. What’s more, continuous insulation that has been added to an entire building structure (connecting roof, walls and foundation) will prevent the passage of air through the building envelope, mitigating thermal bridging in wall assemblies, keeping interior temperatures more uniform and reducing energy demand.
An example of such a building is at Sto Corp’s headquarters in Weizen, in Germany’s Baden-Württemberg region. Building 15 was designed as an oval – in the style of the Sto pail – and is used as an entrance and reception building with meeting rooms and communal spaces. The new reception building reflects the high value that the company places on sustainability. The declared aim was to achieve a zero-energy-standard building, an objective that was able to be achieved thanks to the exceptional energy concept.
By combining various measures to reduce energy requirements and using innovative technology to meet the demand, the concept creates comfortable indoor climate conditions without impacting the environment. Measures include high thermal protection, external solar protection, airtight building envelope, effective use of daylight and LED lighting, window ventilation and heat recovery system among other features.
Regardless of the label or certification, energy efficient buildings are now becoming the standard rather than the stand-out. As technology advances and innovations like continuous insulation wall systems are available to the building industry, zero-energy buildings are becoming far more attainable.