Upcoming Tour

Come and see the geothermal system, the ERV, the solar-power net zero meter, the many recycled and recycled-content materials or anything else about sustainable design and modern homes that may have caught your interest. To fulfill a LEED requirement that encourages public awareness of the LEED program and its homes, Modern Atlanta will be hosting an open house in early May. The house will be completely furnishes and open to the public. Please keep it on your calendar and email us for specific information!

RainShine House Atlanta Introduction

The RainShine house is a two-story, 2800-square foot, three-bedroom, 3 ½ bath home located in Decatur, Georgia on a 1/3 acre infill lot and currently under construction. Homes in the surrounding single-family neighborhood are of mixed vintage ranging primarily from the 1920’s to post war. Located 1 1/2 blocks from downtown Decatur, RainShine is in a very walkable neighborhood convenient to shopping, great restaurants, excellent transportation options, many other community resources and a remarkable diversity of cultural opportunities.

The project site was specifically selected to allow the owners to pursue their preferred lifestyle of walking, biking and using mass transit in their day-to-day lives. For them, minimizing their dependency on personal automobiles will result in fewer car trips and thus contribute to less pollution, congestion, less use of imported oil, and a healthier, more community-oriented lifestyle. RainShine, however, does occupy a challenging 1/3 acre site. Although the property is within sight of the subcontinental divide, buildable area is constrained by a man made flood plain (resulting from poor municipal culvert design and a huge nearby asphalt church parking lot with inadequate runoff controls), a sewer easement transversing the site and the usual residential zoning setbacks. These factors result in a trapezoidal shaped 3,778 square foot area available for building. The house, porches and decks of the home are tightly defined within these limitations.

RainShine is contemporary in design and is named for key design features. The living room, dining, kitchen and guest bedrooms are sheltered by a unique butterfly roof structured with steel beams spanned by exposed 1 ½” tongue-and-groove wood decking. The roof floats above continuous clerestories allowing light to flood into the interior. Light shelves around the clerestory sills bounce and diffuse natural light throughout the interior. The butterfly roof is designed to capture rainfall (Rain) for a rainharvest system located in the basement and is oriented to maximize southern exposure for a roof mounted photovoltaic system (Shine). The butterfly design, with it’s inverted gable, simplifies rainwater collection, eliminates extensive gutter and downspout systems and the associated maintenance headaches common in conventional gabled or hip roofed homes.

Occupying the front of the lot is the entrance foyer and a two-story living room overlooked by a sleeping loft and two guest bedrooms. Dining room and kitchen flow in an open manner to the living room. The single-level master suite with his and hers baths extends to the more private rear of the lot and shares with the living area a large, covered south-facing deck. A screened porch cantilevers off the living room, engages the street and in conjunction with the living room serve to screen the private rear portion of the site. There is a full semi-conditioned utility basement containing all systems. A drive consisting of wheel strips of site salvaged brick borders the north property line. Since automotive accomodations are not a major consideration in the owner’s lives, no garage was required. However, a bike rack does terminate the drive.

The home features commercial-grade thermally broken aluminum storefront with large expanses of glass and operable windows strategically located for natural ventilation. Operable clerestory windows are remotely controlled and are designed to create a stack effect allowing extended natural ventilation periods during the spring and fall without reliance on hvac systems. 

Interior spaces are visually demised and defined by “thick walls” containing storage, book shelves, niches, pass-throughs, closets, audio visual equipment, systems, etc. Except for certain utility areas, interior walls stop short of ceilings and are topped by glazing systems thus visually completing the floating roof effect and enhancing distribution of daylight refracting from the clerestory light shelves. Interior materials and finishes are VOC free and many were, in the spirit of reducing the home’s carbon footpring, selected for recycled content, local manufacture or were site or locally salvaged. For example, the wood floors, comprising over 90% of the floor area, are sawn from locally salvaged old growth heart pine. The nine foot high exterior doors are fabricated from the same material.

December '08

The drywall is being installed and mudded, steel is being painted.

Photovoltaic System Layout

The panels face south for optimal solar exposure.

Interior Images

Exterior Images

Natural Ventilation

The house has been designed to be comfortable at certain times of the year without heating or air conditioning. The owners prefer to use HVAC as little as possible, and, in this climate, with proper ventilation, none is required for extended periods in the spring and fall. The house is made comfortable without air conditioning via cross-ventilation, incorporation of the chimney effect in higher spaces, ceiling fans, and excellent insulation. Additionally, a screened porch off of the Living Room has been incorporated into the design of the house. The screen porch is a traditional southern house feature that allows for mosquito-free outdoor comfort and privacy much of the year.

The house itself has been designed for natural ventilation with strategically placed operable windows with screens. Remotely operated windows in the clerestories create the chimney effect.

Documentation and Verification: In the primary living areas natural ventilation is achieved as follows:

• Over 12% in operable window area/conditioned floor area in the Master Bedroom in addition to a pair of screened French doors to a covered deck.

• Over 12% operable area/conditioned floor area in the remaining primary living areas (Living Room, Dining Room, Kitchen, Bed Rooms). Operable area achieved through inclusion of one door from the Living Area to the Screened Porch.

• At least two windows in each habitable room are on opposite or adjacent walls.

• Insect screens installed on all operable windows.

• Ceiling fans in all primary living areas.

Quantifying the contribution of natural ventilation:

• There are physical principles that control the flow of air in a house that is referred to as natural ventilation. Our discussion can focus on “Stack driven ventilation”. Wikipedia has a good discussion under “Natural Ventilation” and refers to an equation in ASHRAE. We have verified that our ASHRAE Fundamentals are the same equation. This equation (see attached) estimates the stack flow in cfs (cubic feet per second) as a function of parameters. Inside and outside temperatures are two controlling variables. If the inside temperature equals the outside temperature the delta T goes to zero and there is no stack flow. The temperature contribution is expressed as ((Ti- To)/ Ti) where temperature is expressed as Absolute Temperatures (Deg R) i.e. (460 + degrees F). 

• To have a stack flow the T inside must be greater than the outside temperature. A comfortable inside temperature range is, say, 70º to 85º F. To have a stack flow the outside temperature must be lower than these temperatures, say, 65º to 80º F. The weather bin temperatures tell us historically the hours per year that Atlanta can expect to have outside temperatures in this range. These hours are expressed in five-degree F bands as follows for the following temperature: (Note: our earlier Equipment Performance Bins reports show these same values.)