Passive Design Goes Beyond Sustainability
Passive house design delivers healthier and energy-efficient homes that lower costs while supporting climate responsiveness and regenerative communities.
Today’s land planners, developers and builders are finding that simply being driven by sustainability will not answer the upcoming generations’ demand for homes that are rooted in their need for better health, comfort and climate responsiveness. Passive house design focuses on creating highly energy-efficient buildings that minimize the requirement of active heating and cooling systems.
Passive design is achieved through a combination of architectural design principles, high-performance building components and meticulous attention to detail. It goes beyond ordinary “green” or “sustainable” construction efforts. The ultimate goal is to create a home with a comfortable and healthy indoor environment while significantly lowering energy consumption and cost, by also creating an environmental impact.
Holistic Planning
As with most of life, what is beneficial to humans is generally beneficial to the natural world, and if done right, can contribute positively to ecological systems. Constructing holistic communities with healthier, more comfortable homes will also lead to more eco-friendly and regenerative environments. Passive house design achieves this goal by implementing several key principles and elements, including planning techniques, product selection, smart technology and local cultural practices. Certification organizations, such as the National Green Building Standard (NGBS) and Passive House Institute U.S. (PHIUS) ensures that buildings meet rigorous performance standards which is one way to get more holistic results, promoting prescriptive standards vs performance-based standards. For example, homes with dark siding don’t perform as well as homes with light siding, primarily due to increased heat absorption.
Land development and urban planning is the beginning of a regenerative process where cultural and community needs, patterns and resources can be identified and addressed. Research across continents indicates that walkable, mixed-use living increases social connectedness while having a positive impact on energy consumption by lowering transportation requirements. In addition, by using local materials, crafts and trades, people reactivate local supply chains and techniques. For example; earth vaulting, stone masonry and lime plastering can lower carbon-intensive footprints. Understanding the sun’s rotation relative to the property to determine proper homesites on each parcel and window placement, also adds to passive house design. Other passive solar planning techniques include shading with trees, overhangs and awnings.
Construction and Design
Product selection for passive house design is key. For example, these houses feature significantly more insulation than conventional buildings to minimize heat transfer through walls, roofs and floors. Natural insulation materials, like wool and mycelium, have excellent thermal and acoustic properties and are fire-resistant, moisture regulating and biodegradable. High-performance windows and doors, with photo-, electro- or thermochromic glass or multiple layers of glazing and insulated frames, minimize heat loss and solar gain. In addition, studies show that occupants benefit from reduced eyestrain from glare, fewer headaches, less drowsiness and better-quality sleep. Automated shades can also provide control of the sun, as well as provide occupants with feelings of security and safety. Another product consideration includes using materials on the exterior of the house with high thermal mass, particularly those local to the region, like stone and concrete. These materials help to moderate interior temperatures by absorbing and releasing heat slowly.
Careful, detailed construction practices require paying attention to specifics. For instance, insulation must be properly installed to avoid thermal bridges, which are areas where insulation is interrupted, allowing heat to escape or enter the building. Especially with balanced ventilation systems, air tightness is crucial. If leaks and drafts are not prevented, energy efficiency and indoor comfort can be compromised. In some regions adding an HRV (Heat Recovery Ventilation) or ERV (Energy Recovery Ventilation) system can add energy savings by recovering energy from outgoing air connected to a mechanical ventilation system.
Enhanced Home
The overall benefits to passive house design start with energy savings by reducing heating and cooling requirements. With the correct systems, products and practices energy needs can be up to 90% lower than conventionally constructed buildings. However, lower energy bills for home occupants are simply the beginning. Passive house design provides dwellers with increased comfort with consistent interior temperatures, improved indoor air quality with continuous filtered and purified air and increased durability achieved with high-quality, regional construction with attention to detail. Added to these benefits, is the level of sustainability that rises beyond conventional “green” construction to achieve regenerative goals for the enhancement of the environment.
By Jillian Pritchard Cooke from our September/ October Issue of Green Home Builder