Reimagining Built Ecologies: Novel Framework for solar-water building envelope systems for year-round water security, thermal management, and daylighting
Date of Award
Spring 2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Architecture
First Advisor
Dyson, Anna
Abstract
Water insecurity is a global challenge irrespective of a country’s development index, the extent of its infrastructure, or regional water availability. Lack of access to safe drinking water affects almost one-third of the global population. An estimated 2.2 billion people are at risk of contracting easily preventable waterborne diseases such as diarrhea, the third leading cause of death in children under five. Although large-scale water infrastructure has fundamentally improved public health since the 19th century, the paradigm of centralized modern water systems is becoming increasingly indefensible because they are not commensurate with available regional resources in the majority of climates. The infeasibility of depleting resources to meet demand endangers geopolitical relations and worsens inequitable water access through increased water pricing and water quality violations. This thesis investigates the potential shift to a decentralized paradigm of water management that enables a tightly coupled relationship between available ambient water resources and adaptation. Through integrated architectural systems that collect and redistribute bioclimatic resources, environmentally sensitive responses to the provision of energy and water needs of households are examined through building envelopes that capture and purify water while shaping the luminous and thermal environment. The approach is a departure from the technical context of modern, single-function systems such as conventional Household Water Treatment Systems (HWTS). Used by over a third of households in water-insecure regions, HWTS provide limited protection against specific pathogens, particularly viruses, inducing user mistrust with persistent waterborne disease exposure and prolonging the general depreciation of the viability of on-site solar water approaches. Furthermore, they are standalone devices that require space, fuel, and costly input materials and miss the synergistic value of integrating solar capture, rainwater harvesting, and storage within building envelopes, which provide critical assets for future net-zero systems for energy, heat, light, and comfort. Research Proposition: Novel Framework for Solar-Water Building Envelope Systems for Year-Round Water Security, Thermal Management, and Daylighting This research takes a fundamentally different, embodied approach towards collecting and shaping ambient energy and water by integrating visible biologically based water treatment processes into the aesthetic design criteria for building envelope and glazing systems. Resource insecurity is addressed ecosystemically by collecting and shaping on-site energy and water resources to furnish the indoor ecosystem with clean drinking water, thermal comfort, and daylighting. Building upon research in the Solar Enclosure for Water Reuse (SEWR) Framework previously developed at the Center for Architecture Science and Ecology (CASE) and the Yale Center for Ecosystems + Architecture (Yale CEA), this dissertation incorporates decades of research in adaptive building facades, optical physics, material science, and chemistry to demonstrate for the first time how low-cost modifications to the building envelope and roof systems could provide photoreactor conditions for novel plant-based photosensitizer-enhanced Solar Water Disinfection (SODIS) and solar pasteurization (SOPAS) to increase the viability of on-site water treatment using renewable plant-based materials. A system proposition is developed and demonstrated for low-income households within three bioclimatic field sites: Phoenix, Arizona; Cape Town, South Africa; and Lake Atitlan, Guatemala. Experimentation within each field site evaluated the system performance, including water disinfection capacity, solar heating, and daylighting. The novel design combines solar concentration and plant-based photosensitization to reduce the time to inactivate waterborne viruses from more than 6 hours for conventional solar disinfection to less than 10 minutes. Incorporating several water treatment mechanisms, the system overcomes the limited availability of sunlight across wet and dry seasons by leveraging broad-spectrum solar energy for effective expedited treatment. Modeled extrapolation of the field data showed that even during non-optimal solar periods, a 1 m2 system provides a minimum of 15 L per person daily potable water annually, meeting UN minimum drinking water requirements. The synergistic benefits also extend to the provision of hot water and daylighting, delivering up to 80-95% of annual domestic hot water demands in temperate to arid climates and reducing glare compared to conventional double-glazed skylights, permitting large fenestration areas and adequate cool daylighting (10% Tsol, 10-20% Fenestration ratio). Impact and Future work These findings could transform distributed water systems for urban areas lacking safe water supply by providing year-round water safety and heating without dependence on grid-based energy or off-site consumables, forging resiliency, benefiting household security and between water-energy-food nexus systems in the built environment. Furthermore, to meet the requirements for net-zero households, the integrated approach maximizes the potential for exterior roofs and walls to simultaneously deliver clean energy, water, and daylighting. Future work will investigate architectural integration to assess the potential for distributed urban water systems to transform global water security through widespread adoption across housing types.
Recommended Citation
Pretorius, Mandi, "Reimagining Built Ecologies: Novel Framework for solar-water building envelope systems for year-round water security, thermal management, and daylighting" (2024). Yale Graduate School of Arts and Sciences Dissertations. 1330.
https://elischolar.library.yale.edu/gsas_dissertations/1330
