Johnson-Chronister Residence
Project type: Single-Family
Project size: 0
Cost/sq ft: $0
Completion date: December 01, 2005

Project Goals

The Johnson/Chronister residence was designed to be sustainable and environmentally responsive. The plumbing fixtures are water conserving, and overall water consumption is greatly reduced by the spray irrigation septic system. Many recycled and local materials were used, along with a soy-based total fill insulation at the roof deck, and a 14.0 SEER heat pump.

The highly sloped terrain provided quite a challenging site for this new home. The view, the terrain, and the trees are all accounted for in a very site-specific and unique design that is flexible enough for future growth. The concept of the home is that of an old English Manor that has been added onto over time. The timeless architecture adds comfort and warmth to an already spectacular site. To complement the old world architecture, antique and salvaged materials are abundant, showcased by hundred year old french doors and stained glass windows, and antique door knobs and plates.

Project Description

This home features a passive solar technique called a cupola, which functions as a thermal chimney. The cupola, or thermal chimney, is based on an ancient concept of air movement that man has utilized for hundreds of years. The idea is very simple, at the highest point of the house, build a "chimney" that allows hot air to rise (which it does naturally) out of the house. Hot air escapes through the operable windows in the chimney, and cooler air is drawn into the home from the lower portions of the house and ground, by natural convection. Other passive solar concepts that work well in a hot/humid climate include proper orientation, building overhangs, and daylighting. During a hot summer, one thing we need to be comfortable is a lot air movement over our skin. Good natural ventilation is especially critical if you want to limit the use of air conditioning. However, in the hottest part of the year, breezes can be slow and humidity can be very high. This is why it is important to create good natural ventilation on at least two sides of a room, preferably opposite sides, which allows air to flow in and out rapidly.

Project Features

Energy:

  • Operable thermal chimney
  • 150 compact fluorescent fixtures
  • 14 SEER heat pump, with ducts inside thermal envelope, fresh air ventilation
  • 600 square feet per ton of cooling
  • Shading on east and west walls
  • Total fill bio-based insulation in walls and roof
  • Insulated, low-E, double paned windows
  • ENERGYSTAR® appliances

Materials:

  • Cast earth in first floor walls
  • Bio-base total fill insulation
  • 100 year old salvaged French doors, salvaged doors, door hardware
  • Reused and salvaged wood and other materials

Water:

  • 90% of the existing vegetation was undisturbed
  • Spray irrigation septic system covers zoysia turf grass
  • 90% of new plants are from the current City of Austin WaterWise or Grow Green Plant list
  • Aerobic waste water uses spray irrigation on turfgrass

Health and Safety:

  • Formaldehyde free insulation
  • Hard-surface flooring throughout
  • Thermostat/humidistat runs unit for dehumidification
  • Super low VOC paints

Community:

  • Existing community
  • Pervious driveway
  • Built-in recycling center and backyard compost bin

Commissioning and Testing/Results:

  • Equipment Sizing Summary: System designed at 609 square feet per ton which achieves efficient dehumidification
  • Blower Door Test: 0.33 ACH (air change per hour)
  • Duct Blaster Test: Ductwork located within conditioned space; test not required

Last Updated: 12/30/14
Project Team
The challenging building site allowed the architect to create a unique design.

The cupola functions as a thermal chimney. It allows hot air to escape and draws in cooler air using natural convection.

An interior view of the thermal chimney located over the kitchen island (center).