OVERVIEW

USGBC 2010 Natural Talent Design Competition and the Salvation Army created this competition to focus on LEED for Homes, affordable housing, universal design and functionality for elderly occupants. We are proud to be a part of the effort to assist New Orleans and Broadmoor residents with redeveloping after hurricane Katrina. We have focused our design on providing a low construction cost through prefabrication and a low energy cost with PV panels to greatly reduce energy bills. We believe that this design provides all types of owners at different stages of life with a safe, flexible, high-quality home. We know through incorporating sustainable design elements inside and outside the home we can facilitate community discussions and change perceptions about what it means to have a green house.

EXTERIOR

Our team was faced with several challenges when designing the exterior spaces, building envelope and relationship to the street. The Broadmoor neighborhood consists largely of bungalow and shotgun homes built on or slightly above grade. Since hurricane Katrina, homes are now required to have finished floors a minimum of seven (7) feet above ground level. This produced challenges not only with matching neighboring homes but also with ADA accessibility. Our Bungalow style home is typical of the area with large front and rear porches for residents to sit out on and interact with neighbors and passersby. The ADA access problem had only two reasonable solutions; an extremely long ramp or wheelchair lift. Our design incorporates a wheelchair lift in a ground level closet. This not only allows elderly persons to easily access their home but also gives the building a sense of grounding and reduces the feeling that the house was simply placed upon stilts. To further reduce the ‘beach-house’ feeling the home has gardens, a variegated screen wall and siding that extends to the ground all of the way around the building.

The building envelope consists of steel structurally insulated panels (SIPS). These SIPS consist of two steel sheet metal skins laminated to four inches of insulating foam for walls and six inches of foam for roofs. The system provides a fully thermally broken envelope for highly efficient insulation. There are no studs, or rafters to act as conductors for hot, cold or moisture transfer through the building. Not only do SIPS provide superior insulating properties but structurally the steel skins stand up to flying debris and other hazards experienced during a hurricane. Finally, the light weight of the panels and their prefabricated design provide for simple construction.

Outside of the SIPS the building is clad with wood slats to provide color and additional neighborhood character to the building. This wood siding is not only decorative; it has been designed to slide in places to act as hurricane shutters over the windows. Residents only need to reach outside of the window, pull the shutter across to the locked position and their windows will be well protected from debris. Additionally, hurricane protective straps anchor the building to wooden pilings and ensure that the structure stays sound during high winds.

The gardens are to be planted with locally native plants and grasses. These plants will not require any irrigation or special care to thrive in the unique New Orleans climate. In the rear of the house is situated a raised planting bed for residents to grow their own fruits and vegetables. Rain barrels collect water from the roof structure to store plenty of water for irrigating any plants that are not native in the planters during times of drought.

INTERIOR DESIGN

Once inside the house the resident is faced with a highly efficient 2 bedroom, 1.5 bathroom floor plan. At the front entrance is a coat closet and place to keep shoes so that dirt is not tracked into the house. Further into the house the main space opens up with a full kitchen, dining and living area. An abundance of windows and the high vaulted ceilings give this space a large, open and inviting feeling where residents can feel comfortable as they go about daily routines. The master bedroom is sufficiently large to allow for ADA access to both sides of a queen sized bed. Two closets with pocket doors separate the master and guest bedroom. At the rear of the house the guest bedroom has been designed to function equally as a home office for younger residents or others looking to work from home. Both of the restrooms are ADA accessible with low flow fixtures and in-wall blocking for grab-bars to be added if needed.

An interior design is only as good as the finishes, in this case the building is outfit with many sustainable materials. In all public spaces the floors are made from pressed bamboo. This product grows at an astonishing rate for a high level of sustainability while looking and wearing just as good as old-growth hardwood floors. Cabinets and trim work are all made from FSC certified woods ensuring that he forests are properly cared for while being harvested. Recycled carpet and tile materials also perform as well as their less green counterparts while helping reduce waste. All paints, stains and adhesives used inside the building are low VOC materials ensuring that the indoor air quality remains high.

The home has been designed for residents of all ages and abilities. Principals of universal design have lead to a fully ADA compliant building. The addition of a wheelchair lift allows persons with disabilities an easy access path to their home without the labor of using an exceptionally long ramp. Furthermore, the kitchen has been designed with removable cabinetry at the sink and range to allow for a wheelchair bound person to have full access. The bathrooms include ADA compliant fixtures, grab bars and sufficient room to maneuver about. All rooms and pathways in the house have been designed to be accessed by a person in a wheelchair. Additionally, the planter in the back yard is at a raised elevation allowing elderly persons the ability to easily reach in to tend to their garden.

PRE-FABRICATION

The need for abundant, low cost and high performance housing in Broadmoor and New Orleans in general lends itself naturally to modular construction or prefabrication. From conversations with several industry experts and abundant research we have found that prefabrication can save 20% of construction costs. In a factory setting factors such as weather, worker productivity and layout and highly controlled. Materials may be bought in bulk at a discount and tools are readily available. Most importantly worker productivity is maximized by proper layout and the ability to build in an assembly line fashion where each worker becomes a specialist instead of a ‘jack of all trades’ as is seen in field construction.

For this project, the building envelope, interior finishes and porches can be constructed ahead of time and assembled on-site. The building has been designed with a double built-up beam under the floors to allow easy setting on foundation pilings. Similarly a double ridge beam is used to support the peaked roof. This double construction allows the building to be split down the middle, loaded onto trucks and delivered to the site.

While the building is being constructed in the factory the site can be prepared by driving wood pilings into the ground and landscaping. The site work can be completed simultaneously by a separate specialized crew saving vast amounts of time and money. Once the site is ready, trucks with the home arrive along with a crane to be placed onto the pilings. With the building attached to the foundation it can be securely connected and trimmed out on the inside. Porches also constructed in a factory can then be delivered and attached.

HVAC

The HVAC system proposed for this house employs two strategies to reduce energy consumption and improve indoor air quality. The first strategy utilized is a natural ventilation system. The natural ventilation system is a good candidate for this house because it has a low relative cost, uses zero energy and greatly increases the amount of ventilation and fresh air. This greatly increases the indoor air quality. This system takes advantage of the mild spring, fall and winter months to cool and ventilate the house for free. The natural ventilation system works by taking advantage of the natural buoyancy of air. As the air in the house is heated up by windows, people or appliances, it rises to the top of the high vaulted ceilings. The warm air then exits the house through small roof vents. As this warm air rises and exits the house, cooler outdoor air is introduced in to the space through open windows. This outdoor air cools and ventilates the house as it travels upward to start the cycle over again. Ceiling fans are placed in the vaulted ceilings to help induce this air movement and extend the natural ventilation season.

Since the climate of New Orleans is not conducive to natural ventilation all year round (high heat and high humidity in the summer) a second ventilation method is needed for maximum comfort. This second HVAC strategy uses a multi-zone heat pump system that will cool the house in the mid summer months, and heat the house in the dead of winter. This system is superior to a standard house heat pump system or furnace because it uses multiple indoor "zoned" units that heat and cool rooms independently. Our system uses three separate "zones" based on space usage and locations. The master bedroom will have its own thermostat and heat pump unit, and the large multipurpose room will have two separate heat pumps to control each area independently. Combined with programmable thermostats on each "zoned" unit, this system will heat or cool each room independently and only when occupied. A conventional, single zone heat pump or furnace will heat or cool the every room in the house, regardless of occupancy. This type of system wastes a considerable amount of energy. The heat pumps that we intend to use for this project are the Mitsubishi model number MXZ-3A30NA (outdoor), and SEZ-KD09NA (indoor - qty 3) This unit has an efficiency rating of 14.5 SEER which is higher than the 13 SEER required by LEED EAcr6.1. This unit uses R-410a which is a non-CFC refrigerant and has a very low ozone depletion rate and global warming potential. This helped the team achieve EAcr11.

This system will also take advantage of simultaneous heating and cooling. If one room needs cooling and another needs heat, the multi-zone heat pump will simply transfer the heat from one room to another the thus producing practically free heating and cooling! The heat pump system was arranged so that the system will pull return air from directly next to the kitchen area. This will take care of any kitchen odors and improve the indoor air quality.

The thermostats used in this house will be Prolifix brand programmable thermostats. These thermostats have internet capability and are completely programmable. This allows the user to set heating and cooling schedules for each room to optimize efficiency. It also allows them to change their settings or see their room temperatures through a standard web browser.

The occupant has control over which system he/she wants to use. When the outdoor air conditions are ideal for natural ventilation, a green light will illuminate next to the thermostat. When this green light is on, the occupant is encouraged to open the windows and press a button to open the attic vents and allow the fresh air to naturally cool and ventilate the space. If the occupant is uncomfortable or the outdoor air conditions change, the occupant just needs to close the windows and attic vents and the heat pump system will take over.

Overall the advanced HVAC systems in the house help to achieve EA 1, EA 5, and EA 6 for reduced energy consumption.

ELECTRICAL

The photovoltaic system design which harnesses the energy from the sun in order to deliver sustainable electricity incorporated for this house will provide the owner with the most financial incentives and tax credits available for a residential property in the entire country. These aggressive incentives range from 30% Tax Credits on the Federal level and 50% Tax Credits and exempting Property Taxes on the State level and much more. This 2-3 KW system was designed and thought out to incorporate conservative factors such as taking into account all the fluctuating variables. Such variables can range from additional electronic components introduced to the house during the construction phase in addition to the expected addition of electrical components by the owner over the life span of the house.

Taking up only 250-300 sq. ft. of roof space for photovoltaic array panels this system can provide the owner a return on investment (ROI) in about 6-8 years if not sooner, essentially paying for itself over time. Along with some additional components the system can incorporate methods of supplying electricity back into the utility grid due to the fact that the house generates more electricity than it consumes on a daily basis. This in result will provide the owner of the house with credits on a monthly basis as shown in their electricity bills essentially the electricity company paying the owner directly, a formula that any home owner would love.

The system incorporates equipment such as the photovoltaic (PV) array panels located on the roof, a PV array circuit combiner, ground-fault protector, DC fused switch, DC/AC inverter, AC fused switch which connects to your main utility service which would be the dedicated electrical panel located in the house which is fed from the utility service. While it seems like there are a lot of components to this system each ones serves an important role in providing an efficient and safe electrical service to the house in a sustainable manner and it all can all easily fit within a small closet located next to the main electrical panel. In addition having a battery system backup tied into the system is always an option that an owner can incorporate as well in case of any power outages or emergency scenarios.

Based on the location of this house this system will receive a certain amount of solar radiance also known as solar energy commonly expressed in kilo-watt hours per square meter per day. This value varies based on weather and latitude of a give location. Assuming the national average of electricity costs at $0.11424/KWh the breakdown showed us that this system could be installed with all equipment components and labor at $7.00 per watt. With all these values combined we estimated the 2-3 KW system to be fully installed and operational at a cost of approximately $45,000. With the abundant amount of incentives and tax credits that is available in Louisiana That cost will be cut down by 80% roughly estimated at a final cost $9000.

PLUMBING

The plumbing system employs two strategies to save water and reduce energy consumption. The first strategy is the utilization of "low-flow" type plumbing fixtures. These plumbing fixtures use on average, 30% less water than their standard counterparts. The kitchen sink, bathroom lavatory, water closet, and shower combine to save roughly 5,000 gallons of fresh water every year. These plumbing fixtures were carefully selected to ensure they have low flow rates and blend well with the architectural features of the space. These fixtures help the team achieve WEcr3 for water efficiency

The second plumbing strategy utilized was using an instantaneous water heater in place of a standard tank water heater. These water heaters heat up instantly when needed, instead of storing hot water like conventional water heaters. Conventional storage type water heaters must keep re-heating the water in their tank as it is cooled by the surrounding air. Instantaneous water heaters do not store water and thus do not have to waste energy keeping the water hot. This results in roughly 15% less energy use when compared to traditional, storage type heaters. Two separate instantaneous water heaters were used locally to make sure the hot water reaches the sink instantly and that heat is not wasted in distribution plumbing losses. These water heaters are thermostatically controlled use staged heating elements for precise heating control even at low flow rates. The EX144TC uses two, 7.5 KW heating elements for a total of 15KW of heating power. The EX120TC uses two, 5.75 KW heating elements for a total of 11.5 KW of heating power. This system helped the team achieve EAcr7.3, Efficient Domestic Hot water equipment.

REVIEW

Through the Natural Design Competition our team has developed not only a culturally sensitive, low cost home; we have been able to design a housing solution that will enable residents from all walks of life to enjoy the benefits of a high performance home. Careful integration of neighborhood context, accessible and sustainable design, prefabrication and energy efficiency we feel that our home design will fulfill the needs of New Orleans and the much deserving Broad moor neighborhood.

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