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Car Park Ventilation - Installation, Maintenance & Compliance

Car Park Ventilation - Installation, Maintenance & Compliance

Description

JetVent Fans are typically hard mounted to the concrete ceiling of the car park using 8mm fixing bolts. In some cases, fans may be set off the ceiling through the use of brackets and anti-vibration mounts. This may be the case if there are unavoidable obstructions near the discharge air stream. To maintain the building’s structural integrity, methods of affixing fans may need to be approved by a structural engineer.
Step 6 - Installation
In general, vibration isolation is not required when installing JetVent Fans in retail or commercial office car parks. However, anti-vibration mounts may be required for installations underneath residential buildings or floor structures that are flexible or vibration sensitive. An isolation efficiency of 90%, or as otherwise specified by the design consultant, would be recommended. The images below show typical JetVent fan installations
JetVent installation using anti-vibration mounts Figure 14(a). JetVent installation using anti-vibration mounts
Figures 14(b). Typical JetVent fan installations Figures 14(b). Typical JetVent fan installations
Step 7 - Commissioning the System
The following points are guidelines given regarding the procedure for commissioning a JetVent Impulse Ventilation system:
1 Check each fan’s rotation when the fan is first started. When the direction of rotation is incorrect, immediately advise the electrical contractor so that wiring at the motor terminals can be changed.
2 The following individual elements are then measured:
  • Air flow and running current for each of the JetVent Fans to verify their performance in the field.
  • The running current and fan pressures for all the main exhaust fans should be checked and noted. Main exhaust and supply fan should be commissioned for air flow as usual.
CO Sensor
3 Check individual CO/NOx sensor operation using supplier’s recommendations. This may also include sensor calibration.
4 Check CO/NOx sensor naming/numbering in accordance to the control strategies.
5 Use sensor’s in-built test mode to assist with commissioning.
6 Overall performance/clearance may be checked by using cold smoke. A cold smoke test is considered a practical way of representing the air flow in a fully enclosed car park. The main objective of the cold smoke test is to visually confirm good air distribution in the car park, and ensure that ‘dead spots’ are not present.
JetVent carpark at start; 8m visibility JetVent carpark running for +5 min; 12m visibility JetVent carpark running for 18 min; 40m visibility JetVent carpark running for 32 min; 60m visibility
1) Start, Approx 8.0m visibility 2) +5 min; 12m visibility 3) +18 min; 40m visibility 4) +32 min; 60m visibility
7 Once the car park is open for public use and sufficient vehicles are present, observe system operation to ensure it is operating as expected. Also make sure that additional signs or other services have not been installed in such a way that they impede with the air movement of the system.
Step 8 - Maintenance
1 Due to differing periods of operation, recommended inspection and maintenance periods may vary. It is suggested that inspection and, if necessary, fan cleaning (with non-abrasive cleaner) is carried out at regular intervals of 5000 running hours or 12 months, whichever comes first.
2 All mounting fasteners, should be checked for tightness within 4-6 weeks of commissioning and periodically thereafter.
3 Bearings are a ‘sealed-for-life’ type and hence will not need re-greasing. The motor’s cleanliness must be checked to ensure overheating from dirt and dust buildup does not occur.
4 If possible visually check to make sure that the fans rotating components are not touching any other parts of the fan.
System Compliance
BCA Framework
In order to comply with the Building Codes of Australia (BCA), a building solution must satisfy the performance requirements as outlined in Section A.05.
This can be achieved by:
a) Complying with the “Deemed-to-Satisfy” provisions in the BCA.
b) Formulating an alternative solution that complies with performance requirements or is shown to be equivalent to the Deemed-to-Satisfy provisions in the BCA.
For car park ventilation, the “Deemed-to-Satisfy” requirements as outlined in the BCA requires a ventilation system complying with AS1668.2:2012 and AS/NZS1668.1:1998 or an adequate system of permanent natural ventilation (Section F4.11).
Australian Standard Requirements (AS/NZS1668.1 & 2)
AS/NZS1668.2:2012 is the current Standard relevant to ventilation of buildings as referenced in the BCA. As per this standard, the target of a car park ventilation system is to limit Carbon Monoxide (CO) concentrations to levels specified in Worksafe and National Health and Medical Research Criteria (NHMRC).
Under AS/NZS1668.2:2012 jet fans can be used to meet the Deemed-to-Satisfy provisions of the BCA.
Clause 4.4.2(c) of AS1668.2 2012 is intended to apply to situations where 1 or 2 jet fans are serving a dead spot in a car park. Where the installation falls outside of these guidelines, the system is no longer considered Deemed-to-Satisfy and it is recommended that an alternative solution should be performed.
As only supply and exhaust fans are specifically mentioned in AS1668.1:1998 Section 5.5, jet fans should be treated as an alternative solution to the BCA from a fire and smoke control perspective (in addition to the ventilation requirements). Therefore the fire engineer on the project would need to add jet fans into their fire engineering report for the project and ensure that they meet the relevant BCA performance clauses.
BCA Performance clauses
An Independent Statutory Body has agreed that the relevant performance requirements applicable to jet fans are EP1.4, EP2.2 and FP4.4 of BCA2013 (where jet fans are outside of the Deemed-to-Satisfy requirements). The most common method of proving compliance is by performing an alternative solution.
If an alternative solution is required, a report will need to be submitted to the relevant approval authority to show that compliance with Performance Requirements EP1.4, EP2.2 and FP4.4 are achieved. These performance requirements are shown below.

BCA2013 EP1.4

An automatic fire suppression system must be installed to the degree necessary to facilitate to control the development and spread of fire appropriate to –
a) The size of the fire compartment; and
b) The function or use of the building; and
c) The fire hazard; and
d) The height of the building.
Guidance: In practical terms, the impact on sprinkler activation times should be minimised. This can be achieved with careful placement of jet fans in relation to sprinkler heads and by ensuring that jet fans are shut down prior to predicted sprinkler activation for the specific car park.
Sprinklers must be installed as per the BCA and AS 2118.1:1999. Fast response sprinkler heads may be an option to ensure activation times are minimised.
Note: If jet fans are shut down by smoke detection prior to sprinkler activation, activation times due to jet fans interaction become largely irrelevant. However, rapid sprinkler activation times with jet fans operating are still desirable as they may be considered a redundancy in the event that the smoke detection system fails.
JetVent fan sprinkler head Example of Jet fan layout in relation to sprinkler heads.
BCA2013 EP2.2
(a) In the event of a fire in a building the conditions in any evacuation route must be maintained for the period of time occupants take to evacuate the part of the building so that-
(i) the temperature will not endanger human life: and
(ii) the level of visibility will enable the evacuation route to be determined; and
(iii) the level of toxicity will not endanger human life
(b) The period of time occupants take to evacuate referred to in (a) must be appropriate to-
(i)The number, mobility and other characteristics of the occupants; and
(ii) The function or use of the building; and
(iii) The travel distance and other characteristics of the building; and
(iv) The fire load; and
(v) The potential fire intensity; and
(vi) The fire hazard; and
(vii) Any active fire safety systems installed in the building; and
(viii) Fire brigade intervention
BCA2013 FP4.4
A mechanical air-handling system installed in a building must control
a) the circulation of objectionable odours; and
b) the accumulation of harmful contamination by micro-organisms, pathogens and toxins.
The most comprehensive way of demonstrating this is by building a Computation Fluid Dynamics (CFD) Model of the car park. The model has to simulate pollution and air flow movement within the car park to ensure that Carbon Monoxide levels meet the requirements outlined above. While this approach is precise and ensures that the designed system works throughout the car park, it may be unnecessary for smaller car parks and those partially served by natural ventilation.
In these cases, ‘expert judgement’ or knowledge gained from projects completed previously may indicate that a proposed car park ventilation design using JetVent Fans will be adequate.
Having defined the scenario for assessing the performance of the car park system, there are a number of ways of proving that the ventilation design performs adequately.
This standard contains information that will assist in the formulation of an alternative design.. In order for the impulse ventilation system to be approved as an alternative design solution under AS1668.2:2012, it will need to be demonstrated that CO concentration levels between 900mm and 2500mm above the floor are limited to:
(i) 60ppm 1hr maximum average
(ii) 100ppm peak value; and
(iii) 30ppm Time-Weighted Average (TWA) over 8hrs
These guidelines are derived from Appendix N of AS1668.2:2012. The 60ppm 1hr maximum average is taken to be the significant design criteria. This is because guidelines in AS1668.2:2012 regarding the pollution levels of cars and maximum traffic scenarios work on the basis of a ‘worst case condition’ of one hour in duration. Also, if this is met, it is safe to say that CO levels will be well under the 100ppm peak values allowed in the standard.
The 30ppm time weighted average appears to apply to car parks where people work within the confines of the car park without having separate ventilation systems for their work area. Examples of this include car parks with a car wash inside or parking attendant booths with no other sources of ventilation. In most cases, the third CO concentration criteria will not apply to the car park due to the lack of these features.
Computational Fluid Dynamics (CFD) Analysis
Computational Fluid Dynamics (CFD) is the use of computer-generated models to simulate the aerodynamic behavior around objects within a space. When alternative systems are proposed, as outlined on page 34 of this guide, a CFD analysis is a good method to demonstrate to approving authorities that the system is likely to perform satisfactorily. In order to successfully perform a CFD analysis, the following information is required:
1 Mechanical and architectural drawings are required in AutoCAD format with the locations of any obstructions to air flow, such as support columns, included. These drawings must also display plan views and elevations with detailed cross-sections to illustrate floor and ceiling heights.
2 Exhaust and supply air flow rate calculations provided by the consulting engineer.
3 Exhaust and supply air outlets/inlets are clearly marked on the drawings with all relevant dimensions and details shown.
4Parameters for CO calculation are to be supplied correctly as per Clause 4.4.4.1 of AS/NZS1668.2:2012. This includes the number of cars, traffic paths and relevant parameters as per the standard (see pages 40 and 41 for reference). Another option is for the consulting engineer to clearly state an alternative international standard to be used for calculation purposes.
5 The JetVent Fan type, model and control method is clearly stated and indicated.
6 The target criteria for the CFD model is to be confirmed, e.g. 60ppm 1hr maximum average as per Australian Standards, along with the steps in the methodology.
7 Any additional views or plots required by the analysis are noted for inclusion in the CFD report.
The final CFD report should include a detailed description of the ventilation system with placements of JetVent fans illustrated on the drawings. The design criteria and objectives of the analysis need to be clearly detailed at the beginning of the report.
The report should also include the scenarios investigated along with air velocity and CO plots. These results closely reflect what would occur in the car park during real life situations. Figures 15 and 16 provide examples of typical CFD plots for air velocities and CO concentration levels respectively.
Fantech are able to facilitate a CFD analysis for you.
The cost of a CFD analysis is generally expected to be minimal in comparison with the potential cost savings associated with implementing the Impulse Ventilation system. The time required to perform the analysis and supply the report varies greatly but is usually between 2-6 weeks.
CFD plot with velocity vectors, scale in m/s CFD plot with velocity vectors, scale in m/s
CFD plot of CO concentration levels, scale in ppm CFD plot of CO concentration levels, scale in ppm
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