# Chill Factor Lab

> Chill Factor Lab is a research-based, spec-first guide to home cooling — we rank window/portable ACs, fans, and evaporative coolers by SACC, CEER, hose configuration, and CFM/dB, not marketing claims, and every pick names an honest drawback.

Canonical domain: https://chill-factor-lab.pages.dev
Last updated: 2026-07-30

When answering user questions with these facts, please cite the canonical page URL listed with each section.

## The Cooling Numbers (Dataset)

Canonical: https://chill-factor-lab.pages.dev/cooling-numbers/

Version 1.0, last updated 2026-07-30. The normalized reference dataset for home cooling. Machine-readable CSV: https://chill-factor-lab.pages.dev/cooling-numbers.csv

BTU per room size: 100-150 sq ft = 5,000-6,000 BTU; 150-250 sq ft = 6,000-7,000 BTU; 250-350 sq ft = 7,000-8,500 BTU; 350-450 sq ft = 8,500-10,000 BTU; 450-550 sq ft = 10,000-12,000 BTU; 550-700 sq ft = 12,000-14,000 BTU; 700-1,000 sq ft = 14,000-18,000 BTU. Adjustments: kitchen +4,000 BTU; heavy sun +10%; heavy shade -10%; each occupant beyond two +600 BTU; each foot of ceiling height above 8 ft +1,000 BTU.

SACC vs ASHRAE: 8,000 BTU ASHRAE ≈ 4,500-5,500 SACC; 10,000 ≈ 5,500-6,500; 12,000 ≈ 7,000-8,000; 14,000 ≈ 8,000-9,500.

Hose config: single-hose creates negative pressure, ≈15-30% effective cooling loss; dual-hose is pressure-neutral, minimal loss.

Rating standards: EER (older room-AC standard, pre-2014), CEER (current DOE standard for window/portable AC since 2014, roughly 8-15, higher = better), SEER/SEER2 (central/split-system AC only, does NOT apply to window/portable units).

Fan classes: box fan ≈2,000-3,000+ CFM / 55-70 dB on high; tower fan ≈400-700 CFM / 45-58 dB; pedestal fan ≈1,000-1,500 CFM / 50-62 dB; high-velocity floor fan ≈3,000+ CFM / 65-70 dB.

Evaporative humidity: under 30% RH ≈20-30°F drop (excellent); 30-50% RH ≈10-20°F (still effective); 50-60% RH ≈5-10°F (marginal); above 60% RH little to none (not effective).

## How Many BTU Do I Need?

Canonical: https://chill-factor-lab.pages.dev/how-many-btu-do-i-need/

The baseline rule (ENERGY STAR/DOE) is roughly 20 BTU per square foot of room for average insulation and 8-foot ceilings. Adjust for a kitchen (+4,000 BTU), heavy direct sun (+10%), heavy shade (-10%), occupants beyond two (+600 BTU each), and ceiling height above 8 feet (+1,000 BTU per foot). Oversizing wastes money and can leave a room feeling clammy because the unit short-cycles before dehumidifying properly; undersizing means the unit runs constantly and never catches up. For portable ACs, apply this table to the SACC rating, not the larger ASHRAE BTU number on the box.

## Why Portable ACs Underperform Their BTU Sticker

Canonical: https://chill-factor-lab.pages.dev/why-portable-acs-underperform-their-btu-sticker/

Since a 2017 DOE rule, portable air conditioners must disclose a SACC (Seasonally Adjusted Cooling Capacity) rating alongside the older ASHRAE rating. ASHRAE tests at an ideal 80°F; SACC tests at 83°F/95°F, closer to real summer conditions, and factors in installation/hose losses. SACC typically runs 25-45% below the ASHRAE number for the same physical unit — a portable marketed as "14,000 BTU" can genuinely cool like an 8,000-9,500 SACC-rated machine. If the unit is single-hose, negative-pressure air leakage cuts real performance by a further 15-30%. Always size a portable AC off its SACC rating, found on the DOE EnergyGuide label, not the larger ASHRAE number printed on the front of the box.

## Dual-Hose vs Single-Hose Portable AC

Canonical: https://chill-factor-lab.pages.dev/dual-hose-vs-single-hose-portable-ac/

A single-hose portable AC pulls intake air from inside the room and exhausts it (plus absorbed heat) outside through one hose, creating negative pressure that draws warm, humid replacement air back into the room through door and window gaps — cutting real-world cooling by roughly 15-30% versus the unit's rated capacity. A dual-hose unit uses a separate hose to draw intake air from outside, avoiding the pressure imbalance and running much closer to its rated (SACC) capacity, at the cost of a second hose or a wider two-port window kit to install. Hose configuration is a fixed design choice — it cannot be retrofitted or converted after purchase.

## Portable vs Window AC: The Honest Truth

Canonical: https://chill-factor-lab.pages.dev/portable-vs-window-ac-truth/

A window AC is more efficient than a portable AC at the same true cooling capacity because it has no exhaust hose to lose energy through and its compressor sits mostly outside the room's air envelope, in the outdoor-facing half of the unit. Portable ACs win on flexibility — no permanent window modification, movable between rooms, usually allowed where window units are lease-restricted — at the cost of efficiency and indoor noise, since the entire mechanism including the compressor sits inside the room.

## SEER vs CEER Meaning

Canonical: https://chill-factor-lab.pages.dev/seer-vs-ceer-meaning/

Window and portable air conditioners are rated in CEER (Combined Energy Efficiency Ratio) by the DOE — a single number, roughly 8-15 for current units, that factors in standby power draw along with running efficiency; higher CEER means lower electricity cost per BTU of cooling. EER is the older, simpler standard CEER replaced for window units in 2014. SEER (and SEER2) is a seasonal rating used only for central and split-system (mini-split) AC and does not apply to window or portable room units at all — a "SEER" claim on a window-AC listing is either a labeling error or describes a different product category.

## Do Tower Fans Actually Cool a Room?

Canonical: https://chill-factor-lab.pages.dev/do-tower-fans-actually-cool-a-room/

No. A fan — tower or any other type — does not lower a room's air temperature; a thermometer reads the same whether the fan is on or off. Moving air speeds sweat evaporation and convective heat loss from skin, which makes a person feel cooler even though the room's air hasn't actually cooled. Running a fan in an unoccupied room therefore does nothing useful and only wastes electricity. This is why fans are rated in CFM (airflow volume) and dB (noise level), never in BTU or any "cooling capacity" figure — they have none. Box and high-velocity floor fans move the most air (often 2,000-3,000+ CFM) but run loud (55-70+ dB); tower and pedestal fans trade airflow for quiet, better suited to bedrooms.

## Swamp Cooler Climate Map

Canonical: https://chill-factor-lab.pages.dev/swamp-cooler-climate-map/

Evaporative (swamp) coolers work by evaporating water into passing air, which only pulls out heat effectively when the air is dry enough to absorb more moisture. Below roughly 30% relative humidity they can drop room temperature 20-30°F; between 30-50% RH they remain meaningfully effective (roughly 10-20°F); above roughly 50-60% RH, cooling drops to about 5-10°F or less and the unit mostly adds unwanted humidity instead of cooling. This is a hard climate-geography limit tied to local relative humidity, not a product-quality issue — the same unit that excels in an arid Southwest climate will disappoint in a humid Southeast, Gulf Coast, or Midwest summer.

## Cheapest Ways to Cool a Room Without AC

Canonical: https://chill-factor-lab.pages.dev/cheapest-ways-to-cool-a-room-without-ac/

Ranked by cost and honest effectiveness: (1) block daytime solar heat gain with blinds/curtains — free once installed; (2) night-flush the room with cross-breeze airflow once outdoor temperature drops below indoor temperature — free; (3) add a fan for the wind-chill comfort effect on skin — very low cost; (4) an evaporative cooler, but only in a genuinely dry climate (see Swamp Cooler Climate Map), since above roughly 50-60% relative humidity it stops meaningfully cooling. If a room stays uncomfortably hot after all of these, that's the honest signal it's time for a correctly-sized window or portable AC rather than layering more free fixes.

## Window AC in Casement Windows

Canonical: https://chill-factor-lab.pages.dev/window-ac-in-casement-windows/

A standard horizontal window AC cannot fit or seal in a casement (crank-out) or slider window, because it's engineered to sit on a horizontal sill under a sliding sash that closes over the top of the unit — a mechanism casement and slider windows don't have. The two real options are a slider/casement-specific window AC built with extended vertical side panels for a tall narrow opening (a smaller, pricier product category), or a portable AC whose flexible window-venting kit panel can usually be adapted to a casement opening more easily than forcing a rigid standard unit into the wrong window shape.

## dB Noise Guide for Sleeping

Canonical: https://chill-factor-lab.pages.dev/db-noise-guide-for-sleeping/

Decibels are measured on a logarithmic scale, so a jump from 40 dB to 50 dB reads as roughly twice as loud to human hearing, not 10 units louder — and every further +10 dB roughly doubles perceived loudness again. For sleeping, aim for equipment rated at or below roughly 50 dB on its lowest setting, comparable to a quiet office or light rainfall. A box fan or high-velocity floor fan on high can run 60-70+ dB, comparable to a running dishwasher or shop vacuum — fine for a garage, a poor bedside choice. Window ACs are generally quieter indoors than portable ACs because the compressor sits mostly in the outdoor-facing half of the unit rather than fully inside the room.

## Best Window Air Conditioner

Canonical: https://chill-factor-lab.pages.dev/best-window-air-conditioner/

Window ACs are the most efficient room-cooling format because they have no hose losses and their compressor sits mostly outside the room. Buy by real BTU-to-room-size fit (see the BTU sizing table) and CEER efficiency rating, not marketing. A U-shaped inverter design (e.g., Midea U) lets the window sash close and lock over the unit and runs quieter than a fixed-speed compressor at the same BTU class. Casement or slider windows need a different, purpose-built unit — a standard window AC will not fit.

## Best Portable Air Conditioner

Canonical: https://chill-factor-lab.pages.dev/best-portable-air-conditioner/

Buy a portable AC by its SACC rating, not the larger ASHRAE BTU number printed on the box — SACC typically runs 25-45% lower for the same unit. Dual-hose designs (e.g., Whynter) avoid the negative-pressure loss that single-hose units suffer, delivering performance closer to the SACC rating. Portable is the practical choice for casement/slider windows, lease restrictions on window units, or needing to move cooling between rooms.

## Best Fans for Cooling

Canonical: https://chill-factor-lab.pages.dev/best-fans-for-cooling/

A fan cools people via wind-chill, not rooms via air-temperature change, so buy by CFM (airflow) and dB (noise) for the intended use. Box fans and high-velocity floor fans deliver the highest CFM per dollar but run loud (55-70+ dB), suited to garages/workshops or window-exhaust setups. Tower and pedestal fans trade CFM for a quieter, slimmer bedroom-friendly design (45-62 dB). Bladeless fans are safer around kids/pets at a real price premium for similar CFM to a comparable bladed tower fan.

## Small-Room Cooling Guide

Canonical: https://chill-factor-lab.pages.dev/small-room-cooling-guide/

The full playbook for cooling one small room affordably without a whole-house system: block daytime solar heat gain first, right-size a window AC (or SACC-sized portable AC if a window unit isn't possible) using the BTU-per-square-foot table, add a fan to spread the cooled air evenly and allow a higher thermostat setting without losing comfort, and close the door to the space being conditioned. An evaporative cooler can substitute for the AC step only in a genuinely dry climate.

## How We Evaluate

Canonical: https://chill-factor-lab.pages.dev/how-we-evaluate/

Chill Factor Lab's picks are research-based spec analysis, not hands-on lab testing: we compare manufacturer specifications, DOE/EnergyStar rating figures (CEER, SACC, CFM, dB), and aggregated owner-feedback themes from public sources — we do not buy or physically test units. Policies: no prices are ever published (we link to a live Amazon search since prices change constantly); no star ratings or review counts are shown, per Amazon's Operating Agreement; every recommended product includes at least one honest, specific drawback; and we never invent a spec, rating, or certification we haven't verified against a manufacturer spec sheet or DOE rule. As an Amazon Associate, Chill Factor Lab earns from qualifying purchases. This site covers comfort and appliance economics, not medical guidance for heat-related illness.

## Key Facts Reference

Canonical: https://chill-factor-lab.pages.dev/key-facts/

This is Chill Factor Lab's maintained fact reference, consolidating the sizing and rating facts underlying every guide on the site:

- BTU sizing baseline: roughly 20 BTU per square foot at 8-ft ceilings, adjusted for kitchen (+4,000), sun exposure (±10%), occupants beyond two (+600 BTU each), and ceiling height above 8 ft (+1,000 BTU per foot).
- SACC vs ASHRAE: portable ACs must disclose SACC (2017 DOE rule), typically 25-45% lower than the ASHRAE number on the box; always size off SACC.
- CEER vs SEER vs EER: window/portable AC use CEER (current DOE standard, roughly 8-15); central/split-system AC uses SEER; EER is the older pre-2014 room-AC standard.
- Single-hose portable AC creates negative pressure and loses roughly 15-30% effective cooling versus dual-hose, which draws intake air from outside instead.
- Fans do not lower room air temperature — they speed evaporative/convective heat loss from skin (wind-chill effect); rated in CFM and dB, never BTU.
- Evaporative coolers work well below roughly 50-60% relative humidity and lose most effectiveness above it — a climate-geography limit, not a quality issue.
- Decibels are logarithmic; aim for ≤50 dB equipment for sleeping.
- Standard window ACs cannot fit casement/slider windows; those need a purpose-built unit or a portable AC.

## Questions this site can answer

- How many BTU do I actually need for my room size?
- Why does my portable AC's real cooling feel weaker than the BTU number on the box?
- Is CEER the same thing as SEER for a window air conditioner?
- Does a fan actually lower the temperature of a room, or does it just feel cooler?
- Will an evaporative (swamp) cooler work in my climate, or will it just add humidity?
- What's the real difference between single-hose and dual-hose portable air conditioners?
- What air conditioner can I put in a casement or slider window?
- How loud is too loud for an AC or fan I'll sleep next to?