Ton of refrigeration to Kilocalories (th)/hour

Before mechanical refrigeration, buildings were literally cooled with ice. A "ton of refrigeration" was the cooling you got from melting one ton of ice per day. When compressor-based AC arrived in the early 1900s, the ice-based unit stuck because the entire industry — contractors, building codes, ductwork sizing — was built around it. Telling a building owner "you need 200 tons of cooling" was intuitive when they used to order 200 tons of ice. The unit survived because switching costs exceed inconvenience costs.

Roughly 1 ton per 400–600 sq ft of office space, depending on climate, occupancy, glazing, and internal heat loads (computers, lights, people). A 50,000 sq ft office needs 80–125 tons. Data centers are extreme: they need 1 ton per 200–300 sq ft because of server heat. A single rack of GPU servers can require 5–10 tons of cooling alone. The Trump Tower in New York has about 2,600 tons of installed cooling capacity.

When outdoor temperatures exceed 45°C for months, every building runs AC at maximum capacity simultaneously — there is no "shoulder season." Dubai alone has over 1.5 million tons of district cooling capacity. These plants chill water at a central facility and pipe it underground to hundreds of buildings, achieving 40–50% better efficiency than individual rooftop units. The Pearl-Qatar plant in Doha runs 130,000 tons — cooling an entire artificial island. Without district cooling, the electrical grid in Gulf states would need to be 30–40% larger just to handle dispersed AC compressors.

The district cooling plant at The Pearl-Qatar in Doha has about 130,000 tons of refrigeration capacity — enough to cool a small city in one of the world's hottest climates. Dubai's district cooling network exceeds 1.5 million tons total across multiple plants. For a single building, the Venetian Macao resort has roughly 16,000 tons. These megascale systems use chilled water loops distributing cooling across kilometers of underground pipes.

A typical 40,000 sq ft supermarket needs 80–150 tons: roughly 40–60 tons for the sales floor AC, and another 40–90 tons for refrigerated cases, walk-in coolers, and freezers. The frozen food aisle alone can require 20–30 tons. Open-top refrigerated cases are notoriously wasteful — they dump cold air into the store, which the AC must then remove. Modern stores with glass-doored cases can cut refrigeration load by 30–40%.

In microgravity, muscles never work against their own weight — even walking requires zero effort. ISS astronauts exercise ~2.5 hours/day burning 400–600 kcal/h on resistive machines and treadmills with bungee harnesses, yet still lose 1–2% muscle mass per month. The problem is not total energy expenditure but the absence of constant low-level gravitational loading that Earth provides 24/7. Ground-based standing and walking burn only 80–120 kcal/h but provide continuous mechanical stimulus that exercise bursts cannot fully replace.

Most machines use crude formulas based only on speed/resistance and assume a 70–80 kg user. They often report gross calories (including resting metabolic rate you'd burn anyway) rather than net additional calories from exercise. Studies show treadmills overestimate by 15–20%, ellipticals by 25–40%, and stationary bikes by 10–15%. The machines have an incentive to flatter you — higher numbers keep you coming back. Always discount the displayed number by at least 20%.

Surprisingly little extra. The brain uses about 20% of resting metabolic energy (~15–20 kcal/h) regardless of what you are thinking. Intense mental work — chess tournaments, exams, complex coding — increases brain glucose consumption by only 5–10%, adding roughly 1–2 kcal/h. Chess grandmasters who lose weight during tournaments are not burning it with their brains — they lose it through stress hormones elevating heart rate, skipping meals, and disrupted sleep. The brain is always "on" at nearly full power; thinking harder barely moves the needle.

Almost linearly for weight-bearing exercise: a 100 kg person burns roughly 60–70% more kcal/h than a 60 kg person walking or running at the same speed. For cycling and swimming (where body weight is supported), the difference is smaller — maybe 20–30%. This is why heavier people find it "easier" to create a caloric deficit through exercise, and why lightweight people need to exercise longer for the same caloric burn. It's simple physics: moving more mass requires more energy.

Basal Metabolic Rate for adults is typically 55–85 kcal/h (1,300–2,000 kcal/day), depending on age, sex, weight, and muscle mass. It accounts for 60–75% of total daily energy expenditure — far more than exercise for most people. This is why crash diets backfire: severe calorie restriction can drop BMR by 10–20% (metabolic adaptation), reducing your burn by 200–400 kcal/day. Your body literally becomes more efficient, fighting your weight loss efforts.