2010 USGBC Natural Talent Design Competition
When we think of New Orleans, the first two words that come to mind are community and liveliness. Homes here begin at the porch and end in the backyard, and in either of these locations, neighbors and friends can relax in the shade while enjoying fresh outdoor air. The gathering might begin with a casual conversation on the porch and then move to a more private location in the back. The home facilitates this natural progression by providing expansive indoor/outdoor gathering spaces on the front porch and rear deck, which are connected through a ground level walkway/stair system, an integrated ramping system, and a large indoor connection through the living area of the home. The drought-resistant landscaping surrounding all of these connection points are both inviting to the eyes and sensitive to the environment. For social events, double doors in the front and back of the home open up to add livable space while bringing in the outdoors. In an attempt to maintain the beautiful and historic aesthetics of the neighborhood, we chose a traditional roof pitch in the front that mimics many of the neighboring homes.
Interior Design and Flow
The beauty of a site this narrow and undersized is that it requires creative space efficiency. The first way that we took advantage of the floor space we had was to eliminate hallways and corridor as much as possible. All that remain are vestibules into the bedrooms and bathrooms which remain to maintain privacy. Furniture defines these pathways, providing a feeling of direction and spatial definition while eliminating wasted space. Our design includes a rotating television which serves both the living room and master bedroom. Now you only need one television, and hopefully you don’t need it at all because you’re enjoying the company of your neighbors on the porch. Multi-purpose space was a key driver in the layout. The front room is given a key role in the home as either an office or a second bedroom. The natural light in this space is ideal for either of those purposes. To maintain the resident’s privacy, all bathrooms can be accessed from the living spaces.
Energy and Water Efficiency
This LEED platinum home was designed with energy and water efficiency in mind from the beginning. The tight envelope, high-performance glazing, Advanced Energy Star lighting package, Energy Star appliances and washing machines all work to save on monthly energy costs. For energy efficiency, the back deck is outfitted with a clothes line to encourage occupants to save on drying energy.
The main living area was designed to take advantage of both cross-ventilation and the stack effect. The living area is open from the front of the home to back, allowing for increased cross-ventilation through the doors and windows on either end of the building. On low wind days, ventilators take advantage of the stack effect, where warm air rising to the top of the living space is exhausted, drawing in cooler ambient air through the windows and doors. The master bedroom also takes advantage of these stack ventilators, bringing in cooler air through the window while allowing warmer air to exit through the roof. Extensive shading and strategically placed daylight design limit the amount direct solar gain that occupants experience, increasing the number of hours in the year that the building is able to operate passively.
While New Orleans is a great city for natural ventilation, it does have a significant cooling season with a significant amount of humidity. On days when ambient conditions call for active conditioning, the high-efficiency HVAC system is setup to provide comfort efficiently without a big impact on the environment. In this warm, humid climate, a large proportion of the HVAC energy will go directly to cooling, so meeting this demand efficiently is very important. This system provides efficient cooling by targeting latent cooling. Because of the region’s humidity, a large portion of cooling energy will be used for dehumidification (latent cooling), as the system removes moisture from incoming fresh air. The air conditioner selected for this building includes a rotating enthalpy recovery (desiccant) wheel that removes moisture from incoming air and transfers it to dryer exhaust air. Thus, even when the system is using energy, it does so with great care.
However, the HVAC system does not stop there. Unless operated intelligently, any air-conditioning solution runs the risk of wasting energy as conditioned air is lost unnecessarily through open windows or inefficient envelope sealing. This system tackles this problem with window sensors integrated with the building security system allow the building management system to notify the building owner when the air-conditioning system is active and windows are unintentionally left open and automated dampers close the roof ventilators and help to seal the building.
A solar collector is installed on the roof to provide hot water, and was calculated to provide enough water for use of four residents year-round based on the average climate in New Orleans. A back-up hot water heater provides additional heat if the supply is insufficient. Additionally, the rear south-facing roof is an ideal location and angle for solar collectors, and can be installed there in the future with additional funding.
Realizing the challenge of a fixed and limited budget, we had to make every cent count. We started by analyzing the feasibility of pre-fabrication and advanced framing techniques. Our conclusions were that pre-fabrication would only be cost effective with efficiencies of scale (meaning if we build sixteen of these homes, it starts to make sense, but does not when building only one) and that advanced framing generally was not advisable given the have wind loads in the area. We did decide though, in the spirit of efficiency, that certain advanced framing principles could and should be implemented. With this in mind, we designed to an even module, but maintained 16” o.c. framing rather than 24” o.c. to protect against wind. A modular layout speeds up construction because it is more predictable, and reduces waste because it eliminates closely spaced members. This method of material efficiency reduces waste. We will also use a local recycler to divert all of our construction waste.
Right from the start, construction plays a significant role in indoor air quality. We not only incorporated healthy building materials and finishes into the structural and architectural design, but also created an air quality plan during construction that provides the future homeowner with a healthy living environment. The walls will be coated with non-toxic natural paint, and cabinets and doors will have no added urea-formaldehyde.
Inclusive Design for Elderly Occupants
In designing our home, we attempted to make a space that is easy to navigate and use for all occupants. Once taking either the stairs or the ramp to the living area, all of the spaces are on one level plane, with adequate clearances for wheelchairs. With proper furniture arrangement, a wheelchair can turn around in every room except the laundry room and half bathroom. The full bathroom is based on the ADA Accessibility Guidelines appendix section A4.23.7 figure A7. Kitchen fixtures and appliances can easily be adapted for wheelchair use without affecting the overall layout. Sink faucets in the kitchen and bathrooms will be controlled with lever handles. Door hardware and opening force will also be specified to meet ADA AG requirements. Besides these details, the layout of the house, with its straight path of circulation front to back, is easy to traverse either on a wheelchair or on foot.
The efficiency of the house depends on an informed resident. For effective passive cooling, occupant needs to open the right windows and vents. For active conditioning, the occupant needs to close them. To make sure the house functions properly, the resident would be given a manual for proper ventilation. In addition, sensors would be installed to let the occupant know if windows are open when the air conditioning is on. Included in the budget of the house is a New Homeowner Eco-kit, packed with non-toxic cleaning products, energy-efficient replacement light bulbs, and high-efficiency air filters. When products run out, residents can refer to an included shopping list so that they know what to buy and where it’s available.
In both the structure and the layout, the house was designed to withstand the most severe storms nature has to offer. To resist floods, the floor is located eight feet off the ground. Water can flow freely below the house through the supporting wooden piles. The roof would be fastened to the walls using hurricane clips, keeping the structure intact in the highest winds. The house is provided with abundant shear walls and cross braces to resist lateral wind loads. Hurricane fabric will also be provided as part of the Eco-homeowner kit to hold house elements in place.