PASSIVE HOUSE DESIGN
Passive Houses allow for space heating and cooling related energy savings of up to 90% compared with typical building stock and over 75% compared to average new builds.
Passive building comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. “Maximize your gains, minimize your losses” summarize the approach. To that end, a passive building is designed and built in accordance with these five building-science principles:
Passive house design and energy efficiency begin with insulation. There are 2 basic categories of insulation systems: cavity insulation and continuous insulation.
The more efficient insulation system is Continuous Insulation. What continuous insulation means is that the entire structure has one continuous insulation layer through its entire envelope without any thermal bridging. High-quality insulation in new homes with a smart design is necessary to achieve this.
Cavity Insulation is the more traditional system for insulation and the less efficient of the two. When you put insulation in between wood studs or metal studs, that is cavity insulation. It means the insulation is placed in voids, section by section. In cavity insulation, there is not continuous insulation wrapped around the structure. This means the framing, whether wood or metal, is not actually insulated and can transmit heat through the framing. This is called thermal bridging.
Air Tight Construction
The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air. All buildings and homes have penetrations through the walls and roofs. There are drains, vents, windows, doors, etc. At any location with penetration or opening, you need an airtight seal.
Windows and doors also need to be tested by the manufacturers, and all the product specifications should show the air leakage rates. The lower the air leakage, the better.
After the construction is complete, you can test for air leakage by performing a blower door test. This is a test where a fan is put at an exterior door with an airtight plastic seal and blows air inside. The technician can then use an air pressure gauge to see how airtight the construction actually is. If necessary, the penetrations can be re-caulked or sealed to improve the quality of the seal.
High Performance Windows and Doors
employment of high-performance windows (typically triple-paned) and doors. The insulation value of a window or door is rated by its U Factor. The lower the U Factor, the better.
Use of some form of balanced heat- and moisture-recovery ventilation and use a minimal space conditioning system. If you build an airtight house or building, you need to ventilate it. Install an ERV Energy Recovery Ventilation or HRV Heat Recovery Ventilation systems for efficiency. ERV and HRV use the temperature of the air to be exhausted to preheat or precool the air being brought in.
Solar Heat and Solar Shading
Solar gain is managed to exploit the sun's energy for heating purposes and to minimize it in cooling seasons. The oldest and most basic passive house design principle is solar heating and solar shading. The two most common ways to do this is with trees and overhangs or sunshades. This strategy allows the sun to provide heat in the winter and block it in the summer. The sun is higher in the sky in the summer, and lower in the winter.
Passive building principles can be applied to all building typologies--from single-family homes to apartment buildings to offices and skyscrapers.
Passive design strategy carefully models and balances a comprehensive set of factors including heat emissions from appliances and occupants--to keep the building at comfortable and consistent indoor temperatures throughout the heating and cooling seasons. As a result, passive buildings offer tremendous long -term benefits in addition to energy efficiency:
Superinsulation and airtight construction provides unmatched comfort and even in extreme conditions.
Continuous mechanical ventilation of fresh filtered air assures superb air quality.
A comprehensive systems approach to modeling, design, and construction produces extremely resilient buildings.
Passive building is the best path to Net Zero and Net Positive buildings because it minimizes the load that renewables are required to provide.