Overall HVAC System Strategy
My overall HVAC strategy is to use a combination of passive heating, passive cooling, and air systems to provide heating and cooling to system spaces. Since the dish area receives a lot of day light year round, I wanted to use overhangs in the design as opposed to just using mechanical systems. The use of mechanical systems also contributed to overall energy usage, which I am trying to reduce. Passive heating can be achieved as well using the many glazing features in my design. Additionally, my design encourages visitors to go outside and explore sustainability through the natural world. The greenhouse exhibit will use only passive heating and cooling to explore the use of passive design.
As far as the mechanical systems, I used two Horizontal Split System AHUs of 60000 Btu for the first floor and 30000 Btu for the second floor. They are both located in Storage Room 2 of the second floor because I made 2 storage rooms in my initial conceptual design in the event that I would use one as the mechanical room. This storage room is located on the second floor. I also considered putting the AHU on the roof, but I want to use rooftop solar in the design as well and decided that it would be better to leave more room on the roof for green area and PV solar.
I developed an analytical space and zone schedule as well as a space schedule. In the space schedule, I changed the number of people that I believed fit into each space because sometimes the automatic space capacities assigned in Revit, did not align with what I believed the space capacity realistically was. I developed the specified air flow, actual airflow, and additional airflow needed for the space schedule using HVAC peaks from the Annual Building Energy Usage and HVAC Load Analysis of my design. I then developed the supply and return terminals based on the amount of CFM that each room would need to maintain comfortable and healthy air flow for each user. This image shows the space schedule:
Heating Strategy and Design Implementation
My design takes advantage of passive solar design using glazing. For the greenhouse, I decided to use passive heating entirely since they can take advantage of people’s heat and open glazing systems that plants need. For the Kid’s space, I did not connect the model to the Air Handling Units of the main building, but cooling would mostly be the concern given the amount of heat that can be provided through people occupying the space. Due to time constraints, I chose to model passive cooling for how with the assumption that people will enter and exit the Kid’s zone frequently creating air flow for now. In the future, I would connect the Kid’s zone to an AHU or use thermal mass to cool the space. This image shows the passive design strategies used for the greenhouse which include full glazing systems:
I also decided to change my model from previous designs to have an atrium that will provide more lighting and heating in the sections of the building that make up the interior of the building. This image shows the skylight that I implemented to allow for more heating within an atrium in the inner sections of the building:
Cooling Strategy and Design Implementation
For cooling, my main strategy is to use overhangs in my design, especially for south-facing glazing systems that will receive sunlight most days of the year. I chose to use overhangs because Stanford, CA gets sunlight most days of the year, so mechanical AC would require more energy usage. My design also encourages visitors to spend more time outside in the natural areas of the Dish which would decrease the amount of people in a single building at a time. I still made use of the AHU to further supply the amount of cooling air needed as stated in the Annual Building Energy Usage Analysis. If I were to further explore
Special HVAC System Challenges
I found it especially challenging to model the correct sizing of ducts for all rooms. I think to properly model each room, I would have had to spend so much more time properly inspecting each terminal. For right now, I focused on supplying the necessary air to each room, though maybe more windows or passive air flow strategies can be used instead of mechanical heating and cooling. The atrium of my design also presented an additional constraint in developing the mechanical air flow systems. This picture shows the coordinated systems and architectural model over the atrium:
These images show the architectural and system coordination.
Entrance glazing and mechanical systems:
Passive heating and cooling glazing strategies for the greenhouse and the Kid’s zone: