What is the single most important virtue of a house for the people of the Broadmoor neighborhood?
The house must be ‘easy’.
Each stage within the process of planning and construction of the project, moreover the process of delivery and adaptation of the tenants, shall be simple and easy to follow. The E.A.S.Y. house is easy to build and maintain. It is also easy for the tenants to live in and adjust it to their unique lifestyle. Although the house may not provide every amenity and building system possible up front on completion, it is embedded with infrastructural features that would minimize disturbance to building structure and envelope during the future improvement process. Adding on, the house has simple operating directions which would be easy for the tenants to follow. These design considerations make the house easy, which increases overall efficiency that would directly benefit everyone involved in the project, especially the owners of the house. Such easiness of the house would help the tenant to understand the key features of the house, which eventually would contribute to greater awareness of green buildings to the bigger society. The E.A.S.Y. house will be a ‘model’ house that would initiate the escalation of public interest in green building practices for the benefit of the Broadmoor neighborhood.
The E.A.S.Y. house strives to be ‘easy’ in every way, and yet it still maintains functionality and sense of aesthetics that will ensure the quality of life to the people of Broadmoor. In this matter, the E.A.S.Y. house focuses on four major factors as a house: Efficiency, Accessibility, Safety, and You (the owner).
Efficiency is of great concern throughout the project. Prefabricated SIP (Structural Insulated Panels) wall assembly minimizes the workload and excess material. Modular configuration of building structures into 2’ increments allows the house to be easily built with standardized building materials. Such focus on efficiency during construction allows the project to be feasible under the cost limitation of $100,000. In addition, designing the house to be passively energy efficient, along with the use of ENERGY STAR rated appliances, results in lowering the total energy consumption of the house. Minimized annual energy cost not only helps the house to be sustainable in the long run, but it also greatly contributes to the project’s ability to achieve Platinum certification in USGBC’s LEED Rating System. Efficient use of space is also critical to take full advantage of 880 square feet of limited building area for ensuring the tenant’s comfort and convenience within the house.
Accessibility of occupant is considered in the design. Adequate clearance areas around working stations or entry ways are provided according to the ADA compliance requirements. Universal design guideline was also referenced in specifying building components in their orientations and dimensions. To ensure usability even to handicapped occupants, every operating elements and fixtures are specified to be within the range of reach. Special amenities such as vertical platform lift, grab bars, and lowered closet rails are installed for tenants.
Safety is another important factor as a shelter. Structural integrity against harsh climatic conditions such as hurricanes and floods is critical to ensure the safety of the tenants. Furthermore, resistance to such event prevents further property damage that would otherwise become a financial burden to the owner. Main occupying floor is raised 8’ above grade, on concrete piles. Raised structure prevents damage from floods and protects the building from termites. For added insurance for safety, rooftop is also accessible via mechanical lift and retractable ladder for emergency evacuation. Reinforced structural system using tension cable was employed to secure maximum stability of the envelope of the house as well as to enforce the integrity of each structural member. Multi-functional wood trellis module is also installed to provide added protection of building envelope and structure.
Lastly, and most importantly, the E.A.S.Y. house is designed for ‘you’. ‘You’ represents the actual tenant of the house, the local of the Broadmoor neighborhood in general, and most likely a family of an elderly citizen. Simple yet familiar appearance of the house that faces the streets allows the house to blend well within the existing neighborhood. The building components are mostly modular in dimension and construction to ensure maximum flexibility towards possible renovations by the tenants. Such flexible attribute of the house makes itself easily adjustable to each tenant’s unique lifestyle, and aesthetic preference. As a response to the prevalent porch culture and local people’s general fondness of outdoor spaces, sufficient outdoor porch areas are provided and distributed along the spatial progression of the interior. Porches not only serve merely as outdoor spaces, but also as a point of egress and a mean of expansion of main living spaces. Double hung doors and wide glass sliding doors are installed to maximize openness and accessibility of the porches. Also, to ensure the well-being of the tenants, the rooftop level is accessible to all users which serve as a personal garden with series of planting pots. The structure of the flat roof is specified to hold extra weight for additional dirt and plantings, which makes it easier to improve the rooftop into a green roof. Along with the sufficient area for plantings, design to maximize natural ventilation and specification of zero-VOC construction building materials contribute to better IAQ (Indoor Air Quality) of the house for the better health of the tenants.
The house is divided by two main axes into four zones:
The primary division of spaces is organized to have public area to the south and private area to the north. The main entrance with the porch directly faces the main street to the south. This provides a direct connection between the living space and the neighborhood without sacrificing privacy of bedrooms to the north.
The public / private zone can be physically divided through a pocket sliding door in the middle. This allows downsizing the house based on the occupant’s needs, which increases efficiency of mechanical conditioning for the spaces, as well as providing other benefits such as noise isolation and privacy control. Each zone has dedicated service amenities such as bathroom to ensure usability even when the house is physically separated.
Following the spatial layout of the vernacular shotgun house, the public-private compartments are again divided into service zone to the west and living zone to the east by the main circulation space in the middle. The west service area is dedicated to service functions such as kitchen, bathrooms, and laundry room. East living area is comprised of living room, middle porch, and two bedrooms. In order to maximize the efficient use of space, circulation space is integrated with the service area in the public zone, and with the bedrooms in the private zone. The east orientation of the bedrooms allows for good morning sun and cooler condition during its primary use in the late afternoon.
Within the service zone, ‘wet’ zone is defined by concentrating the programs that demand for hot water around the water heater in mechanical room. Close proximity of these spaces allows for more efficient distribution of hot water with minimum heat loss during the process. Modular dimensional layout of the spaces allows for easy construction, less waste during construction, and flexible configuration of partitions within each zones.
New Orleans is categorized as humid subtropical climate, with short, generally mild winters and hot, humid summers. In January, morning lows average around 43°F (6°C), and daily highs around 62°F (17°C). In July, lows average 74°F (23°C), and highs average 91°F (33°C). The average precipitation is 64.2 inches (1,630 mm) annually; the summer months are the wettest, while October is the driest month. Given this climate, the focus of the house is to increase cooling performance. The house has two modes of cooling operation. The primary strategy is to passively cool the house by natural ventilation with sufficient shading. However, the house can also be mechanically cooled and ventilated as a secondary option in extreme conditions.
Natural ventilation is critical in hot and humid weather as a passive cooling strategy to secure occupant’s thermal comfort. Each space has a dedicated inlet and outlet for outside air to allow sufficient natural ventilation. There are at least three dedicated openings that are of different orientations to maximize cross ventilation. High clearance ceiling in living zones further enhances natural ventilation from stack effect and improves comfort level by isolating hot air from occupant’s level. In addition, ceiling fans can be operated to induce air circulation within the space.
Shading and controlling sunlight is also important in this climate. South facade and porch is covered by a deep overhang roof. Flat roof over the service zone can be a place for a roof garden with a series of planting pots, which also helps to minimize solar heat gain. Modular wood trellis can be easily configured to provide shading to desired location. The trellis system also accommodates as a seasonal green wall which provide extra shading in summer.
An airtight building envelope is achieved with SIP (Structural Insulated Panel) wall construction and with spray-foam insulated wood construction roof and floors. Airtight envelope with sufficient insulation contributes to overall energy efficiency of the house. Mechanical ventilation is provided as a ventilation measure in situations when natural ventilation is not an option, such as in the winter times or during the severe storm.
The house can be mechanically ventilated through an ERV system (Energy Recovery Ventilators), or simple vent fans. The ERV system, when in use, is capable of exchanging heat from inlet air to outlet air, and vice versa. This system can be used year-round, as it can transfer heat from inlet air to outlet air in the summer, whereas the process can be reversed in the winter. Moreover, the system has an integrated desiccant system that provides dehumidification to the indoor air. The ERV system is connected to two sets of supply and return ducts. Each set of ducts is to serve public and private zone respectively. Two sets of ducts are divided by a damper which can be easily operated by the user to further increase efficiency. The ducts are integrated within the wall construction to minimize the obstruction of interior spaces. Ducts run along the circulation corridor, supplying fresh air to the living zones to the east part of the house. Reversely, return duct collects stale and humid air from the service zones located to the west side. The cooler air from the shaded underside of the house is brought in as a fresh supply air for the ERV.
To maximize efficiency of mechanical cooling capacity, ductless split A/C system is provided for the two bedrooms and the living room. The indoor A/C units are installed one for each zone (public and private), which they are connected to a single outdoor unit on the rooftop. These units cool the air by exchanging heat via coolant in liquid form. Liquid is a more efficient medium for transferring energy compared to air, in other words, less volume is needed to transfer the same amount of energy with liquid. Ductless system not only simplifies the construction procedure, but it allows operating independently from the ERV.
Independent operability provides the tenants with more energy efficient conditioning options. In milder seasons where only minimum conditioning is desired, the tenants can operate only the ERV. However, both A/C system and the ERV can be operated during the extreme conditions. When operated in conjunction, the ERV and the A/C unit help each other, creating a synergy effect that increases the efficiency of the overall thermal performance of the house. In addition, ceiling fans also contributes to performance by helping circulation of air within the space.
Green Building Studio was used as energy model software for the project. Estimated annual energy cost of approximately $390. The energy model was generated with the presumption of using 17 SEER/9.6 HSPF Split (Heat pump < 5.5ton) HVAC system with 50°F and 80°F as HDD and CDD thresholds respectively. This figure for annual energy cost is converted to be ENERGY STAR’s energy rating of 54.2% less than average performance of same construction typology. This qualifies to acquire 21 LEED points in EA section, which contributes to the project’s potential of achieving LEED platinum rating. This figure is expected to become even lower with the consideration of the ERV system.
Elevated main floor and underside ventilation minimizes possible radon exposure from soil below.
Use of water-based paint and other certified building material minimizes VOC within the building envelope.
The house has a simple exterior envelope that closely resembles a simple gable roof form, prevalent as a vernacular shotgun house. The simple and rather conservative appearance not only contributes to easier construction but also its familiar form will be more welcoming to elderly occupants of this house. To minimize solar heat gain, bright colors such as yellow (as shown) is used to reflect more light away from surface. Bright and saturated colors also accommodate the weakened color sensitivity of older occupants.
The interior also has a light color finish to reflect and distribute light within the interior space. High clearance and angled roof function as a light reflector that further enhances the day lighting conditions. 12/12 pitch roof is held together with the steel cable system as rafter tie and reinforcement for hurricanes. Moreover, 12/12 pitch (45 degrees) is the optimal roof angle that minimizes the uplift force of the roof structure from the lateral winds.
Tension cable construction method minimizes material use which lowers overall construction cost, provides structural integrity, and allows for high cathedral-ceiling indoors. In addition, the tension cables that span across the living spaces function as railings for hanging horizontal curtains or drapery. These simple curtains not only provide additional shading, but also act as a divider to isolate cooler bottom air from the hotter air that rose to higher level. Moreover, these horizontal curtains create a visual effect that softens the high pitch ceilings in the living spaces, which otherwise some might feel a bit overwhelming or empty. Again, these curtains can easily be replaced with a fabric of the tenant’s preference, and likewise, tension cables can also serve as hangers for light weight decorations in special occasions.
Apertures are preferably located facing the north, to provide daylight with minimum solar heat gain. By having less area of aperture to the south than to the north, more diffused light from north is provided to the indoors and glare is reduced.
North face has greater total aperture area compared to the aperture area on the south face. Having prevalent wind from the south, such difference of aperture area of opposing direction also promotes natural ventilation by inducing a pressure difference.
The middle porch contributes to delivering daylight into the middle part of the long narrow house. Tall living space to the south and overhead wooden trellis shading protects the middle porch from direct exposure of hot summer sun.
Clerestory windows are provided in the bedrooms, and skylights in the service zones for both daylight and natural ventilation. These windows are shaded by the trellis roof to the west. They are operable by the user on the rooftop level. Cleaning, maintenance, and operation of hurricane shutters are also done in the same manner by accessing the rooftop level.
Although the house is located in a relatively quiet neighborhood, its main sound source is from the south street. SIP walls serve as a sound barrier that reflect noises from the surrounding away from the indoors. Furthermore, operable sliding door provides acoustic isolation to the quiet and private bedrooms from the public areas.
Efficient construction is achieved by modular layout of the SIP exterior walls. Modular construction shortens the overall construction time and minimizes construction waste.
Wood trellis module function as railings, as underside covers for raised structures, as shading devices, as hurricane protection from airborne debris, and as supports for a green wall. Multi functionality and modular dimension contributes to efficient use of material (wood) and affordable fabrication. Also, due to its modularity it is easy and cost effective to modify the configuration of wood trellis around the building envelope to the user’s preference. In addition, the wood trellis module can be fabricated with different color, material, and patterns to suit the personal taste.
To protect the house from the hot afternoon sun from the west, the trellis system is extensively installed to the west wall. This also provides an infrastructure for easy adaptation of green wall, which will further enhance the shading effect of the whole house.
Rainwater from roof is collected by the gutters then transferred down through downspouts that are connected to a water cistern for collecting storm water. Total of two cisterns are installed for both northern and southern roof. Collected storm water is utilized as irrigation for gardens under porches. The sizes of the cisterns are considered to match the amount of rainfall caught by the roof area.
Wooden decks of porches have 1/4” gaps between the decking members which let rainwater fall to the garden below. The garden under the porch serves as bio-swale that slows the speed of water infiltration. The gardens will be planted with indigenous species of New Orleans such as Acacia, Hibiscus, Magnolia, and Viburnum.
The house provides several special amenities for the disabled tenants. To ease the access through doors, all doors are specified with panic thresholds with less than 1/4” of height. In addition, operable hardware such as door handle is chosen to be installed rather than conventional door knobs to guarantee comfortable operability to the users. In bedrooms, special clothes hanger is provided in substitution to traditional closet space. This hanger is specifically designed to suit the people on wheelchair by having the hanging rod lowered to the range of reach of 48”. The top of hanging rod is covered with an integrated wall shelf for additional use. Also, by eliminating the need to construct additional enclosing wall and closet door, this furniture allows for more efficient space use and lower construction cost. In bathrooms, grab bars and bathtub seating is installed for elderly and handicapped users.
To help the education process of the tenants about green buildings, simple operation manual will be published. This operation manual will include diagrams and illustrations that explain basic concepts of energy and how to manage its use. Moreover, the manual will include every instruction manual of equipment that is to be installed for the house. In addition to the operation manual, mechanical equipment will have a label that shows its use and methods for operation.