General Statement:
When a couple of “empty-nesters” moved to rural Texas and downsized their home in the mid 2000s, they hadn’t foreseen their needs for intermittent social gatherings and to accommodate an ever-growing extended family. Completed in November 2011, the Gatherin’ Place is an extension of their original “right-sized” living space, sited in a clearing next to their home, always available for impromptu gatherings or planned holiday galas. As a seasonally occupied building for large groups of people, the Gatherin’ Place incorporates climatic adaptations of indigenous buildings in central Texas coupled with modern energy efficiency strategies and systems, all within a reasonable budget.
Key Project Goals:
1. Inspiring and adaptable space for intermittent entertaining:
– Simple spatial arrangement to support various functions
– Demonstrate to visitors the value of great design, using a familiar architectural vocabulary
2. Sensitivity to site:
– Maintaining existing surface water patterns by raising the building on piers
– Building in an area without the removal of any trees and using the trees for shielding and shade
– Southern exposure for gardening and future solar electricity
3. Energy efficiency for a minimal budget:
– Emulating vernacular Texas architecture for climatic responsive techniques including: highly reflective roofing, thermally massive shield walls, wrap-around porch shading, and a pier foundation for under-house ventilation
– Adapting common building practices for a superior building envelope
4. Solar power plant:
– Future 1.5kW solar array will allow the building to be “off the grid”
– Instead of a battery bank, excess solar electricity will supplement the main home
Site Selection:
The prime factor in locating the Gatherin’ Place is its proximity to the existing residence – for ease of access by the residents and their visitors. Fortunately, a natural clearing existed nearby, so native trees were not disturbed. The balance between topography and solar-orientation placed the long axis of the building in a slightly southwesterly direction. Shifting the building as far north as possible allows it to take advantage of the natural shelter of native vegetation while providing south exposure for solar electricity production as well as vegetable gardening.
Energy Use:
The central Texas climate has equal heating and cooling loads, creating two energy-use peaks per year. During its first few months of winter operation (and HVAC system tuning), the Gatherin’ Place has demonstrated an average energy use of 3.25 Btus/sqft/DD. It is more efficient than Energy Star (5 Btu/sqft/DD) but not quite to the level of Passive House (1 Btu/sqft/DD). Energy Usage of 15.4 kBtu/sqft demonstrate a 42.5% energy savings over existing building construction (based on 26.8 kBtu/sqft energy usage by another small guest quarters building on site). Current electricity consumption patterns put the Gatherin’ Place on target to be “off the grid” with the future installation of a 1.5 kW solar array per Solar Opportunity Level (SOL) calculations by AnteMeridiem, Inc.
Passive Systems:
While 100% of the spaces can be cooled and ventilated through operable clerestory windows and doors opened to the screened porch, the climatic conditions in Central Texas only allow for natural venting and cooling during the months of April and October. The majority of the year requires mechanical cooling and heating. Insulation and shielding are the best passive strategies to minimize the use of mechanical systems. In addition to a projected façade, a wrap-around porch and a planned cistern thermal sink, the following assemblies were specifically incorporated to mitigate environmental effects.
Foundation – Concrete Piers to isolate the building envelope from extreme ground temperature fluctuations
Floor – 2×12 advanced-framed and R-30 insulated joists accessible for future electrical and plumbing changes
Walls – 2×4 framing with 2×2 horizontal strapping for thinner (R-23) walls with less thermal bridging than 2×6 advanced framing. Interior finished in reclaimed plank boards. Exterior finished with locally quarried limestone block and reclaimed corrugated metal.
Roof – 2×12 advanced framing with open cell + batt insulation (R-40). Interior finished with reclaimed metal. Exterior finished in highly-reflective standing seam metal for water catchment efficiency and reduced solar heat gain.
Mechanical Systems:
Space conditioning is provided by a single heat pump with a supplemental heat pump on the opposite end of the main space for large gatherings in the peak summer months. Due to the well-sealed envelope, an Energy Recovery Ventilator (ERV) provides fresh-air during periods when doors and windows are closed. For times of low winter occupancy, a modified Rumford fireplace can heat the entire space with a small fire due to its efficient configuration.
Indoor Air Quality:
Although the harsh climatic conditions in central Texas allow for natural venting and cooling only during the months of April and October, the Gatherin’ Place has operable low-E windows in each room. The main passive ventilation strategy for the building pulls cool air in through windows in the accessory rooms and open double doors from the screened porch. Hot air rising from the lower metal roof drives a thermo-siphon effect pulling exhaust air out through operable clerestory windows in the main entertaining space. For seasons when the passive ventilation system is not appropriate, the Energy Recovery Ventilator and spot ventilation fans maintain indoor air quality.
Water Use:
Currently, at the Gatherin’ Place, potable water is used for both domestic purposes and landscape irrigation. All roof gutters and downspouts are tied together for the future installation of three 2,000 gal. cisterns. The cisterns will eventually provide all required irrigation to vegetable beds and other landscaping per Adaptive Rainwater Catchment (ARC) calculations by AnteMeridiem, Inc. In the interim, roof drainage is directed into a perforated overflow pipe draining into a tiered bioswale. All domestic wastewater generated at the Gatherin’ Place is treated onsite in a septic tank with field lines providing irrigation to the south picnic lawn.
Grants / Incentives:
No official grants or incentives were provided for the development of the Gatherin’ Place; though reclaimed building materials, from rusty metal siding to old house doors, were provided by a local rancher: James Boston. Initial and ongoing energy and water analytics is provided by Ante Meridiem, Inc., a California non-profit organization. The Gatherin’ Place was selected for these research initiatives due to its promotion of “design-based cultural learning” by integrating environmental responses from indigenous Texas architecture with advanced building techniques to raise design and energy awareness among rural subcontractors and homeowners.
Post Occupancy:
Ante Meridiem, Inc. continues to provide monitoring and reporting for the Gatherin’ Place via its Energy Behavior Analysis (EBA) software, which is based on owner inputs of cost and usage information from monthly utility bills. The EBA software produces graphic reports of energy and water usage patterns, pollution, and financial fluctuations in an effort to incentivize positive energy behaviors by building occupants. Ante Meridiem, Inc. will continue to monitor the Gatherin’ Place through the future installation of rainwater harvesting and solar electricity systems to document these transitions. Reporting will continue until a consistent annual energy usage pattern is identified.
Additional Info:
www.Meridiem.org/Gatherin_Place