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Comment by elil17 | Hacker News Reader

I work in HVAC and it is very common for larger buildings. They get huge incentives for shedding load during peak hours. Larger buildings also have more tools at their disposal beyond simply the "thermal inertia" of the building itself:

1. Ice thermal storage. You freeze ice at night and melt it during the day to cool your building. Only used for large buildings - check out Chicago's district cooling for an awesome example.

2. Adiabatic and hybrid cooling towers. These are HVAC equipment that can switch between regular and a "wet mode" where they evaporate water to cool the AC coil and reduce electricity usage.

3. Better automation tools. Building automation systems are fully programmable (e.g., switch schedules when outdoor temperature is past a certain threshold), unlike most programmable thermostats which can run a fixed schedule but not much else.

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I recall watching a program on green construction on KQED and the Federal Building in SF and how it was built.

From Wikipedia:

> The building was designed to be a 'green' building consuming less than half the power of a standard office tower. Utilizing natural light to illuminate 80 percent of the building helped it achieve worldwide recognition as the first Federal Building to be certified under the USGBC's Leadership in Energy and Environmental Design (LEED) criteria. Its southern wall is draped with translucent panels of perforated stainless steel (3 by 8 feet in size), intended to accumulate solar heat and thereby create an upward air flow, which in turn causes cooler air to enter the building through sensor-controlled windows, achieving an air conditioning effect. The result has been criticized as unsatisfactory by employees working in the building, which has received low workplace satisfaction ratings.

And an article on it - https://www.govexec.com/pdfs/green/080108gsa.pdf

There are some neat things they tried there.

In Toronto there's a giant cooling system for downtown buildings that uses cold lake water pumped downtown from 83m underwater:https://en.wikipedia.org/wiki/Deep_Lake_Water_Cooling_System. It's being expanded to offer even more cooling with a low carbon footprint.

Very cool! Sort of reminds me of seasonal thermal energy storage: https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storag...

Knowing very little about HVAC, when I worked in higher education I was surprised to learn that some colleges centralize heating and cooling for their entire campus. For example, Harvard has a chilled water plant which cools 75 buildings: https://www.energyandfacilities.harvard.edu/utilities/chille...

Interesting article from the Crimson (student newspaper) from 1978 about their recent-at-the-time move to computerize the heating and cooling systems: https://www.thecrimson.com/article/1978/1/12/the-great-chill...

Edit: fixed unintentionally humorous typo, whoops

You know Harvard's endowment is getting too big when they go out and buy Ganymede.

FYI, when that webpage says "tons" they mean the capacity to freeze a ton of water in one day. So Harvard's CWPs can move enough energy to freeze 20,500 tons of water a day - absolutely humongous!

I spent nearly a decade working across the street from plant #1 without knowing what it was, it just seemed to be an out of place (for the comparatively tiny building it was on) massive cooling setup. When I needed to think, I'd often stare out the window and watch the cooling towers in the summer. It was kind of hypnotic, specifically all the running water. From the angle I was at, I could see pretty well into the cooling towers from above.

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