Retrofitting Window Air Conditioner Cover
Parsons School of Design
R.A.C. is a retrofitting window air conditioner cover designed to solve air, thermal leakage problems, and energy waste in New York City. The project aims to increase building energy efficiency by protecting unnecessary airflow and thermal exchange indoors and outdoors. Furthermore, by using sustainable energy, the project would reduce carbon dioxide emissions. It is designed to enhance the functional and aesthetic elements of existing window air conditioners between the building facade and interior wall and will be permanently installed through the window of a building.
What's the Challenge?
Window Air Conditioner in New York City
"There are holes in our walls."
New York City is expected to experience numerous challenges as a result of climate change. In response to these impending crises, the New York City government and city council have implemented a Green New Deal policy and rules for reacting to Climate Change. Significantly, New York City has focused on managing existing building energy efficiency for reducing green gas emissions and making renewable energy replacing fossil fuels. Regarding this background, the existing window air conditioner in the NYC multi-family building is supposed to be solved. Due to air and thermal leakages through poorly-fitting installations and the openings themselves, heating losses are estimated to cost around $150 million per year in excess fuel use, and result in the emission of around 400,000 tons of carbon dioxide emissions annually. That is to say, existing wall and window air conditioners cause unnecessary energy consumption in New York City.
Background and Context
New York city passed a law for building upgrades and guidelines for retrofitting solutions that save energy and lower carbon dioxide emissions. According to the rules, New York citizen have to reduce greenhouse gas emissions by nearly 40% by the year 2030, and 80% by the year 2050. Among of them, multi-family building has a great opportunities. Multi-family residential properties make up nearly 65% of all city buildings by area and 75% of the total properties in New York City. They are responsible for 54% of the greenhouse gas emissions from buildings overall and 49.5% of overall energy consumption. Furthermore, heating and cooling system accounts for 70% of total energy consumption in multi family buildings.
To reduce carbon dioxide emissions and waste of energy usage, I would like to design a window air conditioner cover for retrofitting existed window air conditioners. The cover would be equipped with a solar panel to collect sustainable energy and mechanism openings to protect air leakage from outside. It is designed to enhance the functional and aesthetic elements of existing window air conditioners between the building façade and interior wall and will be permanently installed through the window of a building.
Interior Temperature Measurement and User Survey
I used a thermometer to check the surface temperatures of the window glass, walls, heater, and air conditioning unit in the bedroom wall of my New York City apartment on March 1, 2021. I discovered that the surface temperature of the air conditioner was lower than that of the closed windows surface. Also, I surveyed 14 people who live in multifamily buildings in New York about the effect of air conditioning on indoor temperature. Most residents said that they felt cold in the winter due to air leakage through air conditioners.
Existing User Experiences in Multifamily Building
Through the research, hot air from outside goes inside the building when they are not in use through the window air conditioner in the summer. So residents constantly turn the air conditioner on to cool the indoor environment. In winter, residents constantly use fossil fuels to prevent the interior room from being chilled by outside air entering through air conditioners. In this ways, people experienced uncomfortable environment through the air leakage from window air conditioner.
The potential stakeholders of this project would be building managers, owners, facade contractors, and HVAC contractor companies. When it comes to controlling the building energy management, the building management company and owner are responsible for reducing carbon dioxide emissions and enhancing the building energy efficiency rating until 2030 based on the Green New Deal. Furthermore, the facade contractors and HVAC contractor companies would be great stakeholders to install and managing the air conditioner. This is because this project must be installed with the owner's permission, and the place where it is installed occupies a space between the exterior wall and the interior of the building by HVAC and facade contractors based on the NYC building code.
Precedent Products; Pros and Cons
There are several air conditioner covers. Even though both fabric air conditioner cover is cheap and easy to install, there is no permanent and durable product. The existing fabric product must be replaced after several rainy days and snow days. Also, when users turn on the air conditioner, users should take off the cover from the air conditioner. This means that the covers would be replaced based on the weather. Therefore, these existing fabric covers are not sustainable products for window air conditioners.
Interview with Experts
Through the interview of experts, I can understand the architectural facade in multifamily building and window air conditioner engineering issues in NYC. Through the Arta Yazdanseta, I learned the energy conservation and how to method building management and method of reducing carbon dioxide emissions through the green wall, retrofitting facade building, Green New Deal in NYC Policy and constrains, Sustainable architecture building design method. With Sujung Choi interview, I learned multifamily building facade and wall details, residential laws and codes in NYC, facade construction method in multifamily building, details of facade and building code. Finally, I would like to learn the air conditioner mechanism and engineering system. Through the Marc-Aurelien Vivant interview, I recognized that the design of air conditioner have to be considered the heating issues when they work
Design Strategy; Standardization
Window air conditioning size and design are not standardized on multifamily apartment building facades in NYC. Even some multifamily buildings are equipped with a different brand on each window air conditioner because the building owner, building management, and resident consider the air conditioner's size and capacity based on the window size and room size. However, the windows of multifamily buildings are standardized, making it possible to design a single-size cover for any air conditioner installed and make a standard unit based on the window size.
Main Cover Design
When an air conditioner is used, the outlet becomes a conduit for cold air to enter a building and warm air to escape. At first I focused on the outlet where air was discharged, testing how the velocity of air released by the air conditioner was related to the shape of the cover. When the air conditioner is covered, hot air cannot escape. The heat will adversely affect the operation of the unit. I explored ways to discharge this hot air efficiently. The speed of air as it relates to different cover shapes was analyzed through the Autodesk CFD program. Keeping air volume, temperature, starting point and input speed constant, I observed that the output speed of air varies greatly depending on the cover vent shape.
Kinetic Vent Design
Above all, I determined that the shape of the cover’s outlet should depend on its intended use. The outlet should be open when the air conditioner is being operated, and the outlet should be closed when the air conditioner is not in use. That way, it can block the unnecessary inflow of outdoor air and leakage of indoor air. The cover vent has a kinetic function for this purpose. Through parametric form studies and sketch models I identified feasible forms of outlets. A realistic prototype of a moving outlet is C. It is easy to open and close, and fully capable of meeting functionality.
Vent Wing Design & Mechanism
I looked at the wings attached to prototype C. According to aerodynamics research, the speed and movement of air vary depending on the shape of the wing. Prototype C’s wings produce the most ideal air flow. With or without the air conditioner operating, the user must have a mechanism for the wings to fold and spread out. I used a mechanism that allows the wings to move together at the same time.
Mechanical thermal generation & Main Cover Vent Design
I learned from my interview with Marc-Aurélien Vivant that when air conditioners operate, they generate much heat. That's why conventional air conditioners have vents on both sides and on top. If air conditioning is to be used, an air inlet must be installed on the sides, top and bottom of the cover, to cool the heat generated by the machine.
I designed a mechanism in which the sides, top, and bottom open at once and applied it to the cover. When the air conditioner is used, hot air is released and cold air cools the unit from within the cover.
Upper Main Part Cover Design
The KPF architect I interviewed, explained that if an air conditioner is mounted on a façade, the top should be slanted to prevent rain and snow from collecting on the unit. My design has an oblique slope until just before the cover meets the window. At that point, the part that is joined to the window has a planar shape.
Indoor Design Modeling
Shown indoors, my cover design is equipped with a tambour door system that allows the resident to slide open the door to use the air conditioner and close the door when the system is off, blocking incoming air from the outside.
Indoor System and Mechanism
I want all the mechanisms to work together at once. In other words, when the user opens the door from the inside, the doors on both sides open, and the vent of the air conditioner opens. To do so, I designed the necessary mechanisms
Structure Design Static Analysis
R.A.C.'s Structure would support the load of the air conditioner and the weight of the cover. I proposed three types of structural design and tested the Structure. To start static analysis in Autodesk fusion 360, I made setting options about materials and force; the three types of structures were made of galvanized steel and give force 150 lbs.
Final Structure Design Prototype
The final Prototype is the third Prototype made of galvanized steel. This structure is the best safety structure to support both air conditioners and R.A.C. The galvanized steel structure is installed inside the R.A.C. That structure acts as a mounting bracket upholding the air conditioner and R.A.C.
Installation Method Research and Final Prototype
User Scenario with R.A.C
Exploded Axonometric Diagram
User Interface of R.A.C
Final Rendering R.A.C