Drew McCathernYour Design Journal entries for this module should highlight your design thinking and analysis results that influenced your decisions about:
- your overall HVAC system strategy
Each level of my building has ~2-5 HVAC zones that are tailored to a specific use (e.g., restrooms, stairwells, classrooms… etc.) to ensure maximum user comfort regardless of the zone.
My overall strategy for those zones is to primarily implement radiant floor heating systems throughout to limit amount of mechanical equipment (e.g., ducts, chillers… etc.) in public spaces. The floor system, coupled with other passive design features (e.g., wind protection, passive solar gain, internal heat gain, and thermal mass) makes up the majority (~80%) of the strategies required to provide comfort to users based on the Climate Consultant output for NYC (see below).
For cooling purposes, I plan to use decentralized heat pumps to provide dehumidification and ventilation where necessary, with ductwork placed below the structural beams in each space (ranging from 10’ to 12’). I opted to use a heat pump vs. other air distribution system because they are more mechanically efficient and consume less energy & space vs. traditional AHU or VAV-based systems with large ductwork.
- your heating strategy and how you implemented it in your design
*See above for comments pertaining to overall strategy*
In a more detailed sense, my building has 3 “cores” that each contain a mechanical room and boiler(s) on the 1st floor. Each boiler supplies all of the water required for its respective core.
Pictures of the radiant floor systems are shown below for floors 1, 2, and 5.
- your cooling strategy and how you implemented it
*See above for comments pertaining to overall strategy*
Similar to the heating systems, each of the cooling components are housed within the cores of the building to limit larger ducts, free up roof space for green roof, PV panels, and additional exhibition opportunities, and reduce the impact to visitors.
- any special HVAC system challenges that you encountered
When running the initial analyses and trying to determine how to properly size my system(s) I got conflicting information from Revit and the other weather-analysis tools highlighted in the module. Revit’s analysis (see snapshot below) determines that my peak cooling loads should be much more substantial than my heating loads (1.2M Btu/hr vs. 700K Btu/hr), which is contrary to the results provided by Climate Consultant (where direct cooling only makes up ~3% of the comfort requirement).
Additionally, in reviewing the analysis I realized I’m losing a lot of heat flow through my curtain walls, so I will reassess which walls add value and if the others can be repurposed (as a different type of exterior wall or as a green wall?)
