House Under a Big Roof
Houston, Texas
Nov 2024
Project Description
As Houston’s climate is closer to that of a tropical one with high humidity and heat, House Under a Big Roof became a project preoccupied with the rubric of sufficiency in terms of energetic performance. Our structural design in relation to the sharing of air between rooms was designed with the intention of achieving sufficiency amidst the difficulty of building in a tropical climate to the more strict and less feasible standards such as the Passivhaus1. Here, sufficiency and openness can perhaps become an alternative way to produce a regional model of climatic architecture.
Umbrella House (かさのいえ), Kazuo Shinohara (篠原一男)
To contextualize the project within the current moment, the reference of Kazuo Shinohara’s residential projects was brought to the table. Identifying compositional qualities of irrationality2 and vagueness3 within the Umbrella House, the discussion hoped to link issues of climate and performance with contemporary arguments about vernacular geometry, material, and structure. A duplication of the basic architectural elements of standard timber framing results. A double-pitched roof geometry supported by laminated nominal lumber posts induces various conditions of air and energy transfer. In contrast to the exacting nature of mass timber, where structure and form are one and the same, the discovered pluralistic reading of form and structure is simultaneously conventional and performative in hopes to shift the aesthetics of energy-efficiency away from high-tech solutions or images of rote sustainability.
Climactic Strategy
Water bath demonstrations of two buoyancy ventilation modes: displacement (left) vs. mixing (right), Salmaan Craig
Leveraging thermal stratification and heat recovery, this project experiments with indoor seasonality to redefine standards of domestic comfort. A plenum module within the thick wall of the core is equipped with split system components, facilitating both active and passive methods of cooling and heating. Cooling utilizes the strategy of displacement ventilation to maintain stratification and exhaust excess heat at the top of the core. Active cooling draws in pre-cooled air at the bottom of the core to reduce energy expenditure for conditioning. Heating, as Salmaan Craig demonstrated in the water bath simulation at McGill University, is an opportunity for heat recovery through “mixing ventilation”4. The upper exhaust remains open, and the ceiling fans help pull hot air down to mix the air in the larger space. Operation in the winter results in a more thermally homogenous atmosphere, and active heating benefits by drawing in pre-heated air that has been homogenized. In all scenarios, the reversible fan within the plenum can turn to target where the inhabitants are.
Structural Design
Materiality and detailing negotiated with the predetermined agenda of sufficiency, specifically through the design of an unsealed envelope. The doubled post and beam system was deployed as a 12’ module with 13.5’ bays at the East and West ends. From the ground, a grid of light concrete pier supports an array of posts and flooring members elevated 2’-6” from the ground. Above that is the first shell, an inner roof that distinguishes the core and the surrounding program, setting up the geometry as the medium for stratified air exchange. A second shell, the outer roof, is weather protection as well as a geometric tool to create thickness for an insulating and ventilating attic space. Topping the house is a third roof for the core, extending vertically to reveal mechanized windows for light and ventilation. Plastered hemp lime stud walls become infill, acting as a breathable barrier as well as an element of moisture control.
Footnotes1: Passivhaus is a energy-efficiency standard from Germany that establishes a metric that pairs circumscribed indoor comfort with ultra-low energy consumption for cooling and heating. The rubric often induces the design of a tightly sealed and conditioned enevelope, a counter-natural approach that we deemed unsuitable given Houston’s sub-tropical climate
2: Shinohara, Kazuo, “Theory of Residential Architecture.” 2G, no.58/59 (2011): 246-259.
3: Chang, Michelle. “Something Vague.” Log, no. 44 (2018): 103–13.
4: Salmaan Craig participated as a juror for the final review of this project on December 3, 2024. We further discussed the efficacy of “mixing ventilation” in a high heat and high humidity context.
Captions
470: Plan with structural grid
475: Section B cutting through two bedrooms and porhces
476: Section C cutting through the common spaces and the hightened core
478: Detailed section A cutting through a bedroom + core sharing a plenum unit and a small private porch
479: Sectional construction details with material callouts
484: Superimposed mechanical, electrical, and plumbing plan. Mechanical fixtures consists of a hydronic coil system assisted with a domestic hot water heated, individual reversible fans and coils within the vertical plenum, as well as low CFM ventilation fans exhausting from the bathrooms to the exterior porches
485: View of approaching the front entrance on the South
490: Construction detail rendering of pier, post, and floor connection
491: Construction detail rendering of post, beam, and roof connection
501: Closeup model image
502: Large model image
*Winner of the Margaret Everson-Fossi Award for best graduate-level design
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