November 30, 2018

Trends in Passive Design in Texas Homes

As the residential new build market continues to move towards green and energy efficient options, Net Zero construction is picking up speed. Net Zero houses—those that generate as much energy as they consume—are becoming increasingly common. There are even entire Net Zero subdivisions being built in Texas cities these days.

When building a Net Zero house, it’s important to ensure it is designed to be as energy efficient as possible from the very beginning before adding renewable energy systems. By reducing a home's energy requirements, Net Zero is easier to achieve.

That's where passive design can come into play.

Using smart building materials to manage heat fluctuations throughout the day, passive design harnesses natural elements to drive energy efficiency and reduce costs.

In Texas, architects are often looking for passive design solutions that help cool homes in the summer and keep them warm in the winter. To achieve this, passive design must focus on building orientation, size, and configuration of windows, and materials and systems that can both heat and cool homes based on seasonal and daily variations.

Managing Direct Energy Gains

Given the large temperature swings throughout the day and the mix of heating and cooling days, Texas is ideally suited to passive house design. In passive design, buildings in the northern hemisphere are designed with south-facing windows to bring in as much sunlight and heat as possible into the home in the winter. 

In the summer, shading systems over these windows block direct sunlight from entering the home, keeping the inside cooler. With more than 300 sunny days in El Paso each year, there's a lot of energy to be gained and the home could be overheated without precautions. Passive houses often incorporate triple-glazed windows, as well as overhangs and shading, to avoid overheating.

For instance, this passive house uses traditional-looking overhangs above windows in direct sunlight, while still incorporating the architectural feel of the home.

Landscaping can also be used to help manage direct energy gains. In colder climates, shade from trees can be a limitation to solar heating, but on hot Texas summer days, strategically planted trees can help manage solar overheating.

Thermal Mass

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One of the key components of passive design is thermal mass. That’s when you use building materials that help to regulate consistent internal temperature even while external conditions change with weather or time of day. Selecting building materials designed with thermal mass in mind is critical to the success of passive design.

Architects and home builders frequently choose natural or traditional building materials like stone, concrete, and brick because of their thermal mass properties. These materials absorb and hold heat better than wood or steel.

If you're looking for an engineered solution, ICF wall systems such as Bautex Blocks and Bautex Wall System use insulated concrete, which is ideally suited to keep Texas homes cooler during summer heat and to preserve warmth on colder winter days. Plus, Bautex products have the added advantage of being more cost effective than many other traditional options.

Night Purging

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“If you're warm, open a window.” We've all been told this at least once in our lives. There is nothing new about night purging as a way to passively cool a space. Night purging is as simple as leaving your windows open at night to help cool off living areas after a warm day.

Passive design uses the basic principle of night purging and then takes it further, bringing in cool night air through ventilators or specifically designed mechanical units. And where these units generate heat through motors, this heat can be recovered and recycled into domestic hot water systems, further lowering energy demands and costs.

Airtightness

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Airtightness is critical to the success of passive design. Why go to all the trouble of building a home that balances its own air temperature if that air is just going to escape out of poorly sealed walls and windows? But improved airtightness also runs the risk of poor ventilation, leaving the indoors feeling stale.

The designers of Texas's first passive house acknowledged this is a complex problem requiring a detailed solution. A heat pump can adjust the indoor temperature as needed while an energy recovery ventilator draws in outdoor air, filters it, circulates and flushes out stale interior air. Finally, a humidifier manages humidity of occupant comfort.

A side benefit of passive design's airtightness requirements is that homes often enjoy improved indoor air quality in comparison to traditionally designed houses. With regular filtration, proper humidity and adequate fresh air exchanges, overall air quality is improved, making passive homes ideally suited for residents with allergies and environmental sensitivities.

 

Are You Ready for Passive Design?

As the demand for passive design and Net Zero communities grows in Texas, it's important to understand the standard requirements and what it will take to go from concept to construction. Bautex's line of ICF alternatives can help get you there. To find out how we can help, contact us today.