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User Requirement Specifications for HVAC Projects
User Requirement Specifications (URS) for HVAC Projects. EHS, GMP, Engineering, Maintenance, Production requirements.
URS, validation
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User Requirement Specifications (URS) for HVAC Projects

User Requirement Specifications for HVAC Projects

1. Introduction


User Requirement Specifications (URS) for HVAC Projects is a mandatory GMP document, according to EU GMP Annex 15, 21 CFR Part 11, PIC/S, and other agencies.

In particular:

The specification for equipment, facilities, utilities or systems should be defined in a URS and/or a functional specification. The essential elements of quality need to be built in at this stage and any GMP risks mitigated to an acceptable level. The URS should be a point of reference throughout the validation life cycle.

EU Guidelines for Good Manufacturing Practice for Medicinal Products for Human and Veterinary Use Annex 15: Qualification and Validation

You can access here from the following link:


We should write and approve URS for any critical equipment or installation. In this post, we will apply the general expected concepts to the particular case of HVAC projects.

2. User Requirement Specifications (URS) for HVAC Projects Key Aspects


We should keep in mind the following key aspects when writing URS related to HVAC:

  • It is a live GMP document. So, all documentation requirements such as change control, approval signature, version control, etc, will apply.
  • The URS shall be written and approved before the design starts.
  • Key parameters shall be defined here and validated in the PQ (Performance Qualification). This is particularly important because it will be part of the most parameters to be validated:
    • Temperature
    • Relative humidity
    • Room classification
    • Air Changes philosophy (See this post)

These parameters need to be general and referred to suites or process steps since we have not developed the layout yet.

  • Differential pressure criteria.
  • Shall establish containment requirements, if applicable.
  • Do not confuse URS with engineering specifications!

3. Who is the “user”?


In fact, the user is not a single person or discipline. A set of stakeholders are part of the writing, reviewing and approval of any URS. These should be the minimum departments involved in this:

  • Production / I+D
  • EHS
  • Maintenance
  • Engineering
  • Automation
  • Quality Assurance
  • Validation


Let’s see some contents provided by the above in the following section.

4. Contents of the URS


4.1. Approval page

As with any GMP document, the URS should contain first of all a review and approval page with signatures, including the revisions control description.


4.2. Description

This section should describe in general terms the context of the project, including the scope. An example would be the following:


“The HVAC system is planned to operate by means of air handling units, by using hot and chilled water, with 100% exterior air or recirculation in accordance with the containment required, grouped by zones and located in the technical area.
Air handling units R-1, R-2 and R-3 will guarantee the room conditions (temperature, humidity, pressure, air changes, particle limits, etc.) specified for the Fill & Finish area rooms”


4.3. EHS Requirements

Although some EHS requirements are not strictly part of the GMP requirements, it is usual to include in the URS all those aspects of the project that EHS will consider. Below are a few examples regarding noise, marking, etc:

  • Noise level requirement: the noise level generated during the operation of the equipment should be a maximum of 75 dB (A) 1 m away from the equipment.
    If this requirement is not achievable, a notification must be provided to evaluate if
    supplier provision for noise attenuation is needed.


  • EHS risk analysis or HAZOP results will define the presence and number of emergency stop push-buttons and resulting actions.


  • Instruction markings and warning signs must be clearly legible and indelible. The colour corresponds to the regulations according to Directive 2006/42/CE. AHUs should include alarms and signals necessary to guarantee the health and safety of
    All labels on machinery must be in English.


  • The AHU must be secured in a stable manner. Movement of the AHU due to vibration or other forces occurring must be excluded. The AHU is fixed in place by the supplier.
    AHU installation will avoid the transmission of vibrations from the AHU to the building.
4.4. GMP Requirements

Perhaps, this is the most important chapter of the URS. Here we will include all the requirements for classification, temperature and differential pressure. We could also include here other company standards.

Here below there are a few examples of this section:

  • Class D rooms HVAC Requirements:
    – Controlled and monitored temperature: 17-26ºC*
    – RH of 30-70% (for these areas)
    – Air change rate: ≥ 20 per hour
    – Fresh air supply rate: 30% for Finish Room
    – Presence of HEPA14 terminal filters
    – Particle levels conforming to class D
    – Overpressure between classes: 10-15 Pa
    – Time recovery rating for class change zones (CNC/D): less than 20 minutes


  • The number of Air Handling Units will be enough to control the production areas. The AHU zoning criteria will be the following:
    • Non-Classified Areas
    • CNC Areas
    • Gowning Areas
    • Buffer Area Class C and related MAL/PAL
    • Finish Area Class C and related MAL/PAL


  • Decontamination: not required
4.5. GMP Requirements (Automation)

Furthermore, if our project is under 21 CFR Part 11, we shall take into account all the requirements included there, such as data integrity, process control, BMS, PMS, etc. A few examples of this:

  • In normal production mode, Standard Operator must not manually change the state (from automatic to manual) of objects from the synoptic display.


  • One summarized alarm per unit in normal operating mode:
    WARNING (if redundant)
    ACTION (if not redundant)
    – any fan fault status
    – emergency stop button actuation
    – power voltage fault
    – fire fault (fire switch is powered off)
    – electronic card fault or control system fault.
    – Filter clogging
    This alarm is always active.


  • The vendor cannot access remotely to the system.


  • The audit trail records the following information for each action that creates, modifies or deletes any relevant GxP data :
    – Identification/link to the associated record/data.
    – who made the change (i.e. user identification),
    – when the change was made (i.e. date/time stamp),
    – action (e.g. creation, modification, deletion, approval…),
    – the reason for the change (unless obvious),
    – the old and new values


  • The system provides a viewable record of historical system users, granted access levels and granted periods.


  • Authorized users have access only to system functionality that is appropriate and necessary for their job role,
    without conflict of interest.
    User groups/roles are defined within the system where each access level has access to specific functional areas using the company standard Active Directory user groups (preferred solution).
    At the minimum, the following user groups/roles are defined :
    A. Administrator
    B. Operator
    C. Supervisor
    D. Maintenance
4.6. Business Requirements

Finally, there is a last chapter, that we could name “Business requirement”. These are not strictly GMP requirements but could affect quality indirectly. Normally, these requirements are part of other company specifications: engineering, maintenance, calibration, etc. Being part of this category has an impact on project quality and cost. Examples of this could be:


  • Company standards of:


  • Outdoor design condition


  • Utilities (electrical, heating, cooling)


  • List of deliverables


  • Etc

5. Conclusions


The aim of this post has been to introduce minimum content for User Requirement Specifications (URS) for HVAC Projects with some examples. Please note that not all the examples are applicable to all projects, and they should only illustrate typical content.

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