Documents to be Submitted

Documents to be Submitted
The following documents are to be submitted to GL for approval. To facilitate a smooth and efficient approval
process they should be submitted electronically via GLOBE. In specific cases and following prior
agreement with GL they can also be submitted in paper form in triplicate. GL reserve its right to ask for
supplementary copies, if deemed necessary:
 ventilation and air condition scheme – accommodation and service spaces
 ventilation system machinery spaces and technical spaces
 ventilation system cargo holds
 details of fire closures and weather tight closures
 details of duct penetrations
 approval information (flexible ducts, fire dampers, duct penetrations)
 principal electrical supply, control and monitoring
 emergency stops of fans

International standards

International standards
For design and construction of ventilation systems the following international standards are recommended
as guidance. The last edition of each standard should be applied.
 ISO 7547, Shipbuilding – Air-conditioning and ventilation of accommodation spaces on board ships
– Design conditions and basis of calculations
 ISO 8861, Shipbuilding – Engine room ventilation in diesel-engined ships – Design requirements
and basis of calculations
 ISO 8862, Air-conditioning and ventilation of machinery control rooms on board ships – Design conditions
and basis of calculations
 ISO 8864, Shipbuilding – Air conditioning and ventilation of wheelhouse on board ships – Design
conditions and basis of calculations
 ISO 9785, Ships and marine technology – Ventilation of cargo spaces where vehicles with internal
combustion are driven
 ISO 9943, Shipbuilding – Ventilation and air-treatment of galleys and pantries with cooking appliances

If duct cleaning

If duct cleaning is determined to be the best option:
1. Hire a duct cleaning contractor who is a member in good standing of the National Air Duct
Cleaning Association. Duct cleaning companies must meet strict requirements to become NADCA
members. Among those requirements, all NADCA Members must have certified Air System Cleaning
Specialists (ASCS) on staff, who have taken and passed the NADCA Certification Examination.
2. PROTECT building occupants during and after duct cleaning:
• Place a filter over supply and return grills to capture dust when HVAC system is placed back into
service after cleaning.
• Perform duct cleaning during hours when the building is unoccupied, such as nights and
weekends.
• Use containment barriers and proper ventilation equipment, such as “negative‐air” machines
equipped with high‐efficiency filters.
• Avoid the use of biocides and sealants. Even EPA‐registered biocides may pose health risks,
including eye, nose, and skin irritation.
• No biocides are currently EPA‐registered for use on fiberglass duct board or fiberglass‐lined
ducts. Both the EPA and NADCA recommend replacing wet or moldy fiberglass duct material.

PREVENTION

PREVENTION of duct contamination is KEY to avoiding problems
Follow these recommendations to avoid the need for costly duct cleaning:
• Perform routine preventive maintenance of HVAC systems, by complying with manufacturer
schedules for changing HVAC filters and cleaning coils and other components.
• During building renovation, seal ductwork to prevent construction dust and debris from entering
the HVAC system.
• New ductwork frequently contains oil and debris. Before new ductwork is connected to the air
handling system, it should be inspected for cleanliness and cleaned if necessary.
• Maintain good housekeeping in occupied spaces.
• Ensure that air intakes are located away from contaminant sources.
• Consider routine inspections of ductwork. The National Air Duct Cleaning Association (NADCA)’s
standard, “Assessment, Cleaning and Restoration of HVAC Systems – ACR 2006,” recommends that
HVAC systems be visually inspected for cleanliness at regular intervals, depending on the building
use. For healthcare facilities, the standard recommends annual inspections of air handling units, as
well as supply and return ductwork

component. BEFORE hiring a duct cleaning contractor, make sure you can answer “YES” to all of these questions:

When is duct cleaning appropriate?
Although the value of regular duct cleaning remains
questionable, the U.S. Environmental Protection
Agency (EPA) and indoor air specialists agree that
duct cleaning (or, in some cases, duct replacement) is
appropriate in the following circumstances:
• Permanent or persistent water damage in ducts
• Slime or microbial growth observed in ducts
• Debris build‐up in ducts that restricts airflow
• Dust discharging from supply diffusers
• Offensive odors originating in ductwork or HVAC
component.
BEFORE hiring a duct cleaning contractor,
make sure you can answer “YES” to all of
these questions:
9 Are there known or observed
contaminants in the ductwork?
9 Have you confirmed the type and
quantity of contaminants based on
testing or observation?
9 Are the contaminants (or their by‐
products) capable of entering occupied
spaces?
9 Have you identified and controlled the
source of the contaminant?
9 Will the duct cleaning effectively
remove, inactivate, or neutralize the
contaminant?
9 Have you considered other options,
such as removal of affected ductwork?
9 Is duct cleaning the only (or most
effective) solution?
In all cases, duct cleaning should be undertaken only after the source of the contaminant has been
identified and controlled. Otherwise, the problem will not go away. For instance, the water source

Latest Findings

Latest Findings
Despite more than two decades of research, there is still not enough evidence to draw solid conclusions
about duct cleaning’s benefits on indoor air quality, occupants’ health, HVAC system performance, or
energy savings, according to a 2010 review of scientific studies on duct cleaning.1 The review did find
clear evidence that ductwork can be contaminated with dust and can act as a reservoir for microbial
growth under normal operating conditions. Yet, even when duct cleaning was extremely efficient at
removing contaminants within ducts, the
effectiveness of reducing indoor air pollutants was
highly variable, and in many cases, post‐cleaning
levels of contaminants were higher than pre‐
cleaning levels.

Introduction

Introduction
In recent years, ventilation duct cleaning has grown into a huge industry, in response to surging public
concern about indoor air pollution. The industry claims that cleaning ductwork can improve indoor air
quality, control molds and other allergens, enhance heating, ventilating, and air‐ conditioning (HVAC)
system performance, and reduce energy costs. Yet there is little scientific evidence to support these
claims, and poor duct cleaning practices can actually cause or increase air quality complaints. This fact
sheet provides guidance on when duct cleaning may be appropriate, how to protect building occupants
during duct cleaning, and how to prevent the conditions that drive facility managers to undertake this
costly procedure.