Reducing Energy Consumption of Residences and Evaluating On Site Outdoor Human Thermal Comfort in a Historic District in a Hot-Arid Climate through Strategic Implementation of Tree Canopies: A Case Study in the Armory Park Neighborhood

Abstract

Historical buildings in their physical architecture, with their grand historic walls are a celebration of time, a story of the past. Beyond their architectural style they reflect the past and hold within them community, memories, and an era of the past that many community members hold dear to their hearts. Generations later stories are told, and if we are lucky, the buildings are still standing, repurposed or rehabilitated, to continue to hold not only history but a continued place to continue to hold future history along with it. Their history is not necessarily woven into the years of the walls themselves, but the memories they hold within them. With global warming and the current energy crisis it is important to prioritize energy efficiency measures to ensure a future availability of resources worldwide. Many energy efficient strategies, since not all are new, are often being implemented in buildings constructed in the past. The innovation on solutions for solving human safety and even human comfort are rooted in the very meaning of architecture from the beginning. It is then of main concern that, nowadays, these clear connection between architecture and environmental strategies are disconnected. Technological innovation has ended up challenging the relationship between environmentalist and historical preservationist. It is perceived that these professionals work in contrasting ends of the architectural fields, when, as it will be demonstrated, historical building in one hand bring simplified understanding of how accurately react to local environments, and on the other hand, state of the art environmental technology can preserve the buildings in better and long-lasting conditions. It is commonly seen that these fundamental approaches to applied knowledge are not collaborating and often it seems that they negate one another. Specifically addressing the neglected areas of deep analysis in the integration of new technologies to historic building, this document states how the field faces barriers for its implementation. Energy efficient strategies currently have the potential to threaten the historic integrity of a building, threatening its removal from the National Register of Historic Places. Developing strategies that compliment both disciplines is a necessity to ensure the protection of our heritage and protect the future of our built environment. Environmental and a historical preservation principles are applied to this research. The Goal is to create a methodology for bringing together the two disciplines to complement one another. This, in turn, has the potential to protect historical architecture and the future of the built environment simultaneously. This research concentrates on a residential home that is a contributing property in the Armory Park Historical District located in Tucson, AZ, which, due to the local environmental condition, faces extreme heat and aridity. The energy efficiency of this house is currently poor due, partially, to the absence of shading neither from architectural features nor from surrounding tree canopy or other vegetation, the latter being a strategy encouraged by historical preservationist. Therefore, this absence exposes the home to the harsh climatic conditions reducing its energy efficiency. A level III energy audit was performed on the home followed by a deep analysis using eQUEST software. Research was conducted to represent Mesquite trees, a successfully grown tree in the region, to create a simulation in eQUEST and study the effects of planting this species around a home and their effects on energy efficiency. It is found that the strategic placement of trees around this historical residence does not allow for solar radiation to affect the conditions of the context and the home itself. This research implemented eight different iterations of tree placements around the home. The iterations varied from one tree to six trees resulting in energy savings ranging from 9.53% to 10.90%. Water consumption to support a mesquite tree during the first four years to establish them was also analyzed. These trees would require 518 gallons of water per year, totaling 2072 gallons over a four-year period. This was then converted into its energy use equivalent in Kwh equating to 777 Kwh per year, or 3108 Kwh total for all four years per tree. Surface temperatures surrounding the home were also taken of the base case and an adjacent home to determine the differences between similar surfaces shaded by tree canopy and one lacking shading, these results reflected in a temperature differential of 30°F. In summary, research through data collection of surface temperatures, climate station analysis, energy audits, and energy simulation software was used to analyze current and simulated conditions. The results demonstrated the benefit of the implementation of strategically placed trees. To support future research, climate stations were implemented to collect data in neighboring homes microclimates, one containing vegetation and shade trees, and the other lacking, for a period of one day. Although this comparative study provided a glimpse at the varied microclimate from one home to the other and how this could affect the structures they surround, this data was not enough to support the differences in climate throughout a calendar year. This one-day pilot must inspire future effort to collect and analyze seasonal, annual and multiyear data for establishing reliable trends and patterns that lead to cost-effective and long-lasting strategies. Long term observations will also optimize the solutions and avoid unnecessary additions to the building that unfairly threaten its Historical Preservation value.