To recap from module 4, I’m planning my building as located at Vista Hermosa Natural Park, a green space just across the 110 freeway from downtown Los Angeles. The Climate Consultant plots generated for this location, being part of California region 9, indicate that active heating is generally required for maximizing occupant comfort, with active cooling being quite inconsequential:
The weather station for this data isn’t located in downtown LA, so I don’t think this data is terribly relevant to my proposed location. The urban heat island effect isn’t visible here, and in my experience, downtown Los Angeles tends to require more cooling than heating to maintain comfort. Regardless, if I accept these plots at face value, I find that active cooling is negligibly useful with active heating alone providing over 97% comfortable hours.
Revisiting Climate Consultant, I see that if I limit my occupancy to a 12-7 schedule (7 AM to 7 PM, providing a two hour buffer before and after a typical 9-5 workday), I’m able to obtain 80% comfortable hours without active heating and only a small number of entirely passive strategies:
The comfort model used by Climate Consultant defines a comfortable temperature as between 68 and 75 degrees Fahrenheit. I wish that, in the name of energy efficiency, I could expand this range, as I would be curious to see how many hours would fall within a wider range of 65 to 85 degrees.
In addition to being an exhibition and education space for the public to learn about sustainability and environmental engineering, I want my building to serve as a model of a sustainable, ultra efficient office space. The primary feature that excites me about my building is its fun, biophilic shape (plus its lichen-covered bioreceptive exterior), but extreme energy efficiency is also important to me.
Several floors of my building are office spaces, with the idea being that the space could be rented out to companies at a discounted rate that were willing to try the experimental experience and provide employee feedback. It may be a non-starter, but I’m curious if it would be possible to make the building actually lack central heating and cooling. I recall my father talking about the 70s energy crisis and President Carter encouraging people to wear sweaters indoors to cut down on gas use for heating.
My building’s roof was initially conceptualized as being almost completely covered in solar panels (>90% coverage), but it would be nice if I could reduce that coverage a bit to allow for some rooftop gardens and walkable green space for the building occupants. That would reduce electricity production, and I anticipate HVAC to be one of the highest draws of electricity (especially given that I refuse to use non-electric options for heating).
I predict that the cooling demand during the warmest portion of each day (when the sun is overhead) will be further reduced by my building’s petals, which provide a significant amount of shading to lower floors.
Proposed Alternatives to HVAC for Low Energy Consumption
One of my original goals was to have my building consume no net energy, with a stretch goal that it would actually produce more energy than it consumed. Given that HVAC is one of the primary components of building energy demand, I’m interested in imposing an extremely minimalistic temperature control regime with only two permanent features:
- Jalousied windows: windows with parallel louvers set in their frames that can be rotated with a crank, allowing adjustable airflow.
- Electric ceiling fans for ventilation and circulation
In some places I’ve visited, such as rural Peru and Malta, most buildings lack any sort of central heating or cooling aside from ceiling fans and open windows. Office workers there seem quite accustomed to working regardless of the temperature, even while wearing formal attire, so I figure that American can grow accustomed to a lack of HVAC for the sake of sustainability.
Beyond this, I want my the employees working in my experimental office space to rely upon mobile and personal thermoregulation options provided by the building:
- Swamp coolers: While working in downtown LA in a machine shop one summer, I observed that swamp coolers were quite effective at keeping us cool and refreshed. These are simply box fans with refillable reservoirs of water and wicking membranes that soak up the water so the air flow of the fan evaporates it. LA is dry enough during most days that this is an effective cooling option. This wouldn’t work in more humid locations where the air is already saturated with moisture.
Swamp coolers come in all sizes, from personal, tabletop devices to larger machines that can cool several people simultaneously.
While conventional air conditioning units and swamp coolers can be tricky to compare directly, a general rule of thumb is that, for a similar amount of perceived cooling (assuming that the air is relatively dry), a swamp cooler will use less than a fifth of the power that an equivalent AC unit would require. One website compares a 5000 W AC to a 700 W equivalent swamp cooler: http://energyriot.com/swamp-coolers-vrs-air-conditioners-energy-savings-of/
- Cooling neck/headbands: As a cross country runner in high school, I practiced every weekday during the summer, even with it was over 100 degrees outside. One thing that helped a lot was wearing a cooling neckband. These bands are made of breathable fabric, with some containing pockets of absorbent beads that can hold a large amount of water relative to their size. As with swamp coolers, these bands cool the user evaporatively, but the cooling happens in direct contact with the user’s head or neck. I found these things to be quite effective, and they can simply be remoistened whenever they are starting to dry out.
- Clothing: The dress code will be kept extremely casual, and all employees will be provided with clothing for both cold and hot weather to wear as they please. Redundant supplies will be kept at the building so employees can change without planning ahead of time.
- Cooling clothing: The dress code will be kept extremely casual and all employees will be provided with lightweight, moisture-wicking clothing designed to keep the wearer cool in hot weather. This style of clothing prevents uncomfortable buildup of sweat and insulates the wearer substantially less than normal everyday clothing (and much less than regular office attire) due to its thin, porous fabric.
- Warm clothing: Employees will also be provided with a variety of insulating, cold-weather clothing including sweaters, jackets, gloves, and hats.
While it may not be quite as convenient as maintaining a narrow room temperature range with an active central heating/cooling system, I think these passive and individualized methods for facilitating occupant comfort will allow me to get by without one. If the year-long experiment shows that employees don’t get used to this system, or that it negatively effects their mood or productivity, then it will be valuable information that conventional HVAC is required nonetheless. Hopefully the experiment will find that these simple methods are effective, or at least that they allow a much wider thermal comfort range than normal, thereby reducing the energy requirements of a present HVAC system.
If I assume that the electrical power used to provide cooling is solely consumed by swamp coolers, it appears that I am conservatively seeing energy savings of approximately 80% given the high energy requirements to operate the compressors of conventional air conditioning units.
I regardless wanted to see what it would be like to plan an HVAC system for my building, so I created a plan for the first floor (which is duplicated to higher floors with only slight modifications to account for the decreasing radius with each floor due to the tower’s inward slope).
My biggest challenge here is a lack of a designated mechanical room to host the air handling unit on each floor. I didn’t think to put in specific mechanical spaces on each floor when I made the architectural model, so I just put the AHU to the side of an elevator shaft. Rather than using it as a breezeway as I originally intended, I may just use the innermost circular room on each floor as a mechanical space and create hallways from building core of restrooms, stairs, and elevators to the outer rooms.
The flexible ducts don’t seem to be rendering properly in some locations, but regardless, I didn’t leave enough for the return air system, which is intersecting my building’s extremely thick insulated flooring on each level. I should probably reduce the floor’s thickness.
Regardless of whether I use a conventional HVAC system, I may want to use the ducting and terminals nonetheless for swamp cooling. Swamp cooler units can be integrated into these systems just like more standard air conditioning units and furnaces.