High Performance Homes
Benefits
The name sounds high-tech, but High-Performance homes rely on their simplicity to deliver their benefits, which include:
Cleaner, more Comfortable Interior air
Superior Durability and Longevity
Resilience to Extreme Weather
Energy Independence is Easy
High Performance Homes accomplish these goals by having:
A design that uses the shapes of windows, walls, and roofs to optimize the amount of energy absorbed from the sun, informed by energy modeling.
An exterior envelope that is air tight, well insulated, and controls moisture.
A heating, cooling, and ventilation system that is carefully planned and sized to maintain an extremely clean, comfortable environment inside.
Characteristics
Schematic Drawing of Ballard Passive House
Burke Passive House
Designing a High Performance Home
A High Performance Home can be built in any architectural style, but there are a few design basics that the best homes follow.
Window and roof geometry are important.
They do most of the work of admitting or reflecting solar energy. High performance homes can have windows anywhere just like an ordinary house - the difference is that we measure the energy impact of every roof overhang and window and use that info to help make the best decisions during design.
Properly shaded windows take full advantage of the fact that the winter sun folllows a lower path across the sky. Overhead shades allow winter sunlight to warm a home’s interior while blocking the summer light that would cause overheating.
The sun’s arc is higher in the summer
Summer Shading
Winter Warming
Natural Light All Year
Simple Geometry is Best - A home with a simple shape holds energy more efficiently. It’s easier to make air-tight and has a higher ratio of structure to insulation.
Energy Modeling - An energy model informs the design of a high performance home.
Inputs:
Climate Data collected from nearby weather stations
Your Home’s Geometry including windows, roofs, walls, and foundation
Materials used in your home including structure, insulation, and finishes
Surrounding Elements like trees, buildlings, and other features
Appliances for heating, cooling, ventilation, water heating, laundry, food storage, and cooking
Occupant Count for figuring energy use
Outputs:
Heat Loss & Gain through each assembly at different times of the year
Energy Needed for space conditioning
Renewable Energy Needed for Grid-Independence
High Performance Homes are Very Air-Tight
All homes leak air through gaps in their skin, and you can measure this reliably. With its doors and windows closed, an ordinary home in a 20mph wind will lose it’s entire volume of air to the outside 3-7 times per hour, sometimes drastically more . High performance homes aim for around 10% of that number.
Air-Tightness Benefits
Air-tightness gives High Performance Homes their durability and efficiency, and sets the stage for healthy and clean indoor air by performing two roles:
Mold Risk Reduction
Your home is very often experiencing differences in outdoor and indoor pressure caused mostly by wind. Air moving through any accidental gaps in a home’s exterior envelope often carries lots of moisture, which can foster the growth of mold when it becomes trapped in the wall.
Mold damage causes structures to slowly fail. When a wall or roof hosts mold spores, the indoor air quality is compromised by their presence. Structures sagging from rot create more unintentional air gaps, and this process can accelerate by its own momentum.
Reduced Escape of Conditioned Air
Air-tight homes need less energy to stay comfortable, because less conditioned air leaks out and less humidity finds its way in.
High Performance Homes are Super-Insulated
With air-tight skin, insulation can be added without fear of mold growing from trapped moisture. Adding insulation to a home is an easy decision - the material is inexpensive, easy to install, and will reduce the size and complexity of your HVAC system.
How much insulation you need depends on the design of the house and the climate in which it’s located. This is determined by building an energy model of the home. If windows and roof are placed to reduce energy loss in the winter and overheating in the summer, then less insulation will be needed.
