Passive design is all the rage in architectural circles these days. Architects offer it because customers want it. It is no more complicated than that. To build a home according to passive design standards, architects have to concentrate on utilizing design strategies and building materials that reduce dependence on mechanical heating and cooling.
In terms of design features, Park City, Utah-based Sparano + Mooney says architects take advantage of every opportunity to maintain comfortable temperatures without having to run the furnace or air conditioner. For example, they might design the angle of a home’s eaves to block the summer sun without preventing winter sunlight from pouring in.
As far as building materials are concerned, passive design calls for things like thick insulation, triple glazed windows, and roof-mounted solar panels. The right building materials can increase energy efficiency even with limited design features in the plans.
Just to give you an idea, here are five features Sparano + Mooney says contribute to passive house design:
1. Energy-Efficient Windows
Windows present a big problem for thermal retention. In older homes built without energy efficiency in mind, it is not unusual for the majority of heat loss to occur through single-glazed windows with poorly constructed frames and sashes. That will not do for an energy-efficient home.
Passive design calls for double- or triple-glazed windows, often with gas between the panes. They offer consistent energy efficiency regardless of exterior temperatures.
2. LED Lighting
LED lighting is generally appreciated by homeowners because it uses significantly less energy compared to incandescent and fluorescent lighting. LED lights also last longer. But from a passive design standpoint, they also boast another important feature: they barely produce any heat.
Incandescent light bulbs produce light through a filament that vibrates with the introduction of electricity. Solar lighting uses electricity to heat a gas contained inside the bulb. In both cases, lighting processes generate heat. In an LED bulb, light is produced by a small diode as electricity runs through it. The light-emitting diode generates very little heat.
3. Trellises and Overhangs
Architects often design buildings with plenty of trellises and overhangs that block the high summer sun. This is possible due to the angle of the sun. During the winter, when the sun’s angle is much lower, the overhangs and trellises are not an issue. Sun can still pour through windows to help warm interior spaces.
4. Tight Thermal Envelopes
In architecture, the thermal envelope is the outer shell of a structure. The tighter the envelope, the more energy-efficient the building is. Passive design calls for as tight an envelope as possible with minimal thermal bridges. Achieving a tight envelope requires thick insulation and limited ventilation.
5. Heat and Moisture Recovery
If you know anything about construction and architectural design, you know ventilation is an important part of designing comfortable and healthy homes. But ventilation conflicts with a tight thermal envelope in passive design. So to get around it, architects build in heat and moisture recovery systems designed to do the same thing.
There is some debate as to whether such systems are an adequate substitute for ventilation. Even if they are, at least a minimal amount of ventilation is required. Passive design calls for limiting it as much as possible.
If you were to hire an architect to design a home based on passive design concepts, you could expect to see all five features included in the plans. You would also see quite a few more. There is certainly no shortage of design features that architects can utilize to make homes more energy efficient.
