Product guide

Cold & Hot Aisle Containment — Layouts, Doors and Fire Release

Q: Does containment replace air conditioning?

No. It improves the efficiency of existing cooling; additional capacity is still needed if the room is short of cooling.

Q: Can containment be retrofitted?

Yes, if the row has consistent height and depth and the ends can accept doors.

Q: What happens to skylights on fire alarm?

They open to let suppressant enter the aisle; the release is tested during commissioning.

Q: Which is better, cold aisle or hot aisle containment?

Cold aisle is easier to retrofit and is the most common choice. Hot aisle can be better for high-density rows and for rooms that use the ceiling as a hot return plenum. The best choice depends on the room layout and the cooling design.

Q: How wide should a contained aisle be?

A 1,200 mm aisle is standard. It allows two people to pass and gives enough room for door swing and equipment installation. Narrower aisles save space but complicate service.

Q: How much energy does containment save?

Typical savings are 10% to 20% of cooling energy, depending on the room, sealing quality and supply air temperature. The biggest gains come from reducing air mixing and raising the chilled water temperature.

Q: Can containment be retrofitted to existing cabinets?

Yes. The modular frame is designed for retrofit. Measure the row, ceiling height and door access, then order the frame, panels and doors as a kit.

Q: Does containment work with a raised floor?

Yes. The frame mounts on the raised floor with adjustable feet, and the tiles are cut for cable and airflow openings. Seal the cuts and the frame base to prevent bypass air.

Containment systems that separate cold supply from hot return, with skylights, doors and fire-release mechanisms.

Quick answer

Aisle containment separates cold supply air from hot return air using a frame, roof panels and end doors. A 1,200 mm aisle, 2,000–2,200 mm frame height and 900 × 2,000 mm doors are typical. Good sealing can cut cooling energy by 10% to 20% and support 25–50 kW row cooling.

Last reviewed: 2026-11-07

Containment is the lowest-cost way to improve cooling efficiency in an existing room. It does not add cooling capacity; it stops the cooling system from wasting capacity on mixed air.

Skylights can open on fire alarm; doors can include access control. The frame is independent of cabinet load-bearing.

Best for

Data centers and computing halls
Existing rooms with hot spots
High-density server rows

Key specifications

Cold vs hot aisle containment

Feature	Cold aisle	Hot aisle
Enclosed space	Cold supply	Hot return
Retrofit	Easier	More demanding
Typical use	Existing rooms	New high-density halls
Fire strategy	Skylights release	Heat/smoke exhaust

How to choose

Survey the row

Check heights, depths, aisle width, ceiling and fire interfaces.

Choose cold or hot

Cold aisle for retrofits; hot aisle for new high-density halls.

Plan fire release

Link skylights to the alarm and test with the fire system.

Cold aisle vs hot aisle containment

Cold aisle containment encloses the cold supply aisle and leaves the hot aisle open to the room. It is common in retrofit projects because the cold aisle is usually the front of the cabinets and easier to enclose.

Hot aisle containment encloses the hot return aisle and leaves the cold aisle open. It can be better for high-density rows and for rooms where the ceiling is used as the hot return plenum. Both types need sealed cable openings and blanking panels.

Sizing the aisle and frame

A 1,200 mm aisle is the standard for data centers. It allows two people to pass and gives room for door swing and equipment installation. The frame height is 2,000 mm to 2,200 mm, matching the cabinet row and the ceiling grid.

Doors are typically 900 mm wide and 2,000 mm high, in sliding or swing versions. Sliding doors save space in tight rooms; swing doors give a wider opening. The frame is aluminum with adjustable feet and does not load the cabinets.

Sealing, airflow and commissioning

The target is to keep leakage below about 5% of the supply airflow. Seal cable openings, blank unused U positions and close gaps at the top and bottom of the row. A pressure difference of 5 Pa to 15 Pa between the cold aisle and the room is a useful check.

Measure the intake temperature at the top, middle and bottom of several cabinets. With good sealing, the variation along the row should be within 1 °C to 2 °C. That allows a higher supply air temperature and better chiller efficiency.

Options and delivery

Options include glass or polycarbonate roof panels, drop-away skylights for fire suppression, LED lighting, brush seals and blanking panels. Typical lead time is 20 to 30 working days after drawing approval.

Aisle containment reference

Item	Typical value	Notes
Aisle width	1,200 mm	Two-person access
Frame height	2,000–2,200 mm	Match cabinet row
Door size	900 × 2,000 mm	Sliding or swing
Roof panel	Glass / PC	70–80% light
Leakage target	<5%	Commissioning
Intake variation	1–2 °C	Along row
Cooling	25–50 kW	Row units
Lead time	20–30 days	After drawing

Cold vs hot aisle

Item	Cold aisle	Hot aisle
Enclosed	Cold supply	Hot return
Retrofit	Easier	Harder
High density	Good	Better
Ceiling plenum	Not required	Often used
Door location	Front of row	Rear of row
Common use	Most projects	High-density rows

Containment options

Option	Choices	Use
Roof	Glass / PC / solid	Light and fire
Skylight	Fixed / drop-away	Fire suppression
Door	Sliding / swing	Space
Seals	Brush / magnetic	Cable gaps
Lighting	LED strip	Service
Control	Door sensor	Monitoring

Frequently asked questions

08 Q&A

Does containment replace air conditioning?

No. It improves the efficiency of existing cooling; additional capacity is still needed if the room is short of cooling.

Can containment be retrofitted?

Yes, if the row has consistent height and depth and the ends can accept doors.

What happens to skylights on fire alarm?

They open to let suppressant enter the aisle; the release is tested during commissioning.

Which is better, cold aisle or hot aisle containment?