Ventilation Rate The airflow and air distribution methods

By admin on November 17th, 2007

Ventilation Rate

The airflow and air distribution methods used in the
kitchen should provide adequate ventilation in the
occupied zone, without disturbing the thermal plume
as it rises into the hood system. The German VDI-2052
standard states that a:
Ventilation rate over 40 vol./h result on the basis of the
heat load, may lead to draughts.
The location of supply and exhaust units are also
important for providing good ventilation. Ventilating
systems should be designed and installed so that the
ventilation air is supplied equally throughout the
occupied zone. Some common faults are to locate the
supply and exhaust units too close to each other,
causing short-circuiting of the air directly from the
supply opening to the exhaust openings. Also, placing
the high velocity supply diffusers too close to the
hood system reduces the ability of the hood system
to provide sufficient capture and containment (C&C) of
the thermal plume.
Recent studies show that the type of air distribution
system utilised affects the amount of exhaust needed
to capture and contain the effluent generated in the
cooking process.

Health There are several studies dealing with cooking

By admin on November 16th, 2007

Health

There are several studies dealing with cooking and
health issues. The survey confirmed that cooking
fumes contain hazardous components in both Western
and Asian types of kitchens. In one study, the fumes
generated by frying pork and beef were found to be
mutagenic. In Asian types of kitchens, a high
concentration of carcinogens in cooking oil fumes has
been discovered. All this indicates that kitchen
workers may be exposed to a relatively high
concentration of airborne impurities and that cooks are
potentially exposed to relatively high levels of
mutagens and carcinogens.
Chinese women are recognised to have a high
incidence of lung cancer despite a low smoking rate
e.g. only 3% of women smoke in Singapore. The
studies carried out show that inhalation of carcinogens
generated during frying of meat may increase the risk
of lung cancer.

The risk was further increased among women stir-
frying meat daily whose kitchens were filled with oily
fumes during cooking. Also, the statistical link
between chronic coughs, phlegm and breathlessness
on exertion and cooking were found.
In addition to that, Cinni Little states, that three
quarters of the population of mainland China alone use
diesel as fuel type instead of town gas or LPG,
causing extensive bronchial and respiratory problems
among kitchen workers, which is possibly exacerbated
by an air stream introduced into the burner mix.

Productivity Labour shortages are the top challenge that

By admin on November 16th, 2007

Productivity

Labour shortages are the top challenge that
commercial restaurants face today. The average age of
a restaurant worker is between 16 and 24 years. In a
recent survey conducted by the National Restaurant
Association in USA, over 52% of respondents said
that finding qualified motivated labour was their main
concern.
Room air temperature affects a person s capacity to
work. Comfortable thermal conditions decrease the
number of accidents occurring in the work place.
When the indoor temperature is too high (over 28 C
in commercial kitchens) the productivity and general
comfort diminish rapidly.
The average restaurant spends about $2,000 yearly on
salaries in the USA, wages and benefits per seat.

The Effect of Air Supply Ventilation effectiveness can

By admin on November 15th, 2007

The Effect of Air Supply

Ventilation effectiveness can be described as the
ability of ventilation system to achieve design
conditions in the space (air temperature, humidity,
concentration of impurities and air velocity) at
minimum energy consumption. Air distribution
methods used in the kitchen should provide adequate
ventilation in the occupied zone, without disturbing the
thermal plume.
In the commercial kitchen environment the supply
airflow rate required to ventilate the space is a major
factor contributing to the system energy consumption.
Traditionally high velocity mixing or low velocity mixing
systems have been used. Now there is a third alternative
that clearly demonstrates improved thermal comfort over
mixing systems, this is displacement ventilation.
The supply air (make-up air) can be delivered to the
kitchen in two ways:
high velocity or mixiing ventilation
low velocity or displacement.

Thermal Comfort, Productivity and Health One reason for

By admin on November 15th, 2007

Thermal Comfort, Productivity and Health

One reason for the low popularity of kitchen work is
the unsatisfactory thermal conditions.
Thermal comfort is a state where a person is satisfied
with the thermal conditions.
The International Organisation for Standardisation
(ISO) specifies such a concept as the predicted
percentage of dissatisfied occupants (PPD) and the
predicted mean vote (PMV) of occupants.
PMV represents a scale from -3 to 3, -from cold to hot -,
with 0 being neutral. PPD tells what percentage of
occupants are likely to be dissatisfied with the thermal
environment. These two concepts take into account four
factors affecting thermal comfort:
air temperature
radiation
air movement
humidity
The percentage of dissatisfied people remains under
10% in neutral conditions if the vertical temperature
difference between the head and the feet is less than
3 C and there are no other non-symmetrical
temperature factors in the space. A temperature
difference of 6-8 C increases the dissatisfied
percentage to 40-70%.
There are also important personal parameters
influencing the thermal comfort (typical values in
kitchen environment in parenthesis):
clothing (0.5 - 0.8 clo)
activity (1.6 - 2.0 met)
Clo expresses the unit of the thermal insulation of
clothing.

Heat Gain and Emissions Inside the Kitchen Cooking

By admin on November 14th, 2007

Heat Gain and Emissions Inside the Kitchen

Cooking can be described as a process that adds heat
to food. As heat is applied to the food, effluent (1) is
released into the surrounding environment. This
effluent release includes water vapour, organic
material released from the food itself, and heat that
was not absorbed by the food being cooked. Often,
when pre-cooked food is reheated, a reduced amount
of effluent is released, but water vapour is still emitted
into the to the surrounding space.
The hot cooking surface (or fluid, such as oil) and
products create thermal air currents (called a thermal
plume) that are received or captured by the hood and
then exhausted. If this thermal plume is not totally
captured and contained by the hood, they become a
heat load to the space.
There are numerous secondary sources of heat in the
kitchen (such as lighting, people, and hot meals) that
contribute to the cooling load.

Initial Design Considerations The modes of heat gain

By admin on November 14th, 2007

Initial Design Considerations

The modes of heat gain in a space may include solar
radiation and heat transfer through the construction
together with heat generated by occupants, lights and
appliances and miscellaneous heat gains as air
infiltration should also be considered.
Sensible heat (or dry heat) is directly added to the
conditioned space by conduction, convection and
radiation. Latent heat gain occurs when moisture is
added to the space (e.g., from vapour emitted by the
cooking process, equipment and occupants). Space
heat gain by radiation is not immediate. Radiant
energy must first be absorbed by the surfaces that
enclose the space (walls, floor, and ceiling) and by the
objects in the space (furniture, people, etc.). As soon
as these surfaces and objects become warmer than
the space air, some of the heat is transferred to the air
in the space by convection (see picture 2).
To calculate a space cooling load, detailed building
design information and weather data at selected
design conditions are required. Generally, the following
information is required:
building characteristics
configuration (e.g, building location)
outdoor design conditions
indoor design conditions
operating schedules
date and time of day
However, in commercial kitchens, cooking processes
contribute the majority of heat gains in the space.

Commercial Kitchen Ventilation Systems The commercial kitchen is

By admin on November 13th, 2007

Commercial Kitchen Ventilation Systems

The commercial kitchen is a unique space where
many different HVAC applications take place within a
single environment. Exhaust, supply, transfer,
refrigeration, building pressurisation and air
conditioning all must be considered in the design of
most commercial kitchens.
It is obvious that the main activity in the commercial
kitchen is the cooking process. This activity generates
heat and effluent that must be captured and
exhausted from the space in order to control odour
and thermal comfort. The kitchen supply air, whether
mechanical or transfer or a combination of both,
should be of an amount that creates a small negative
pressure in the kitchen space. This will avoid odours
and contaminated air escaping into surrounding areas.
Therefore the correct exhaust air flow quantity is
fundamental to ensure good system operation,
thermal comfort and improved IAQ.
Similar considerations should be given to washing-up,
food preparation and serving areas.

DOOR SWIVEL RANGE For proper kitchen planning, it

By admin on November 13th, 2007

DOOR SWIVEL RANGE
For proper kitchen planning, it is absolutely essential the kitchen planer carefully check for refrigerator door

collision
avoidance with adjacent cabinets (especially with their door handles !), countertops, pilasters, neighboring walls

or other
kitchen elements. The illustrations below depict the door swivel range of the FREEDOM COLLECTION refrigerator doors
including mounted door panels of both and 1 in thickness. Make sure that the refrigerators are installed in

such a way
that the doors will not have any collision when opened.
In the event of interference causing collision problems, you have several options to overcome this:
- Limiting the refrigerator door opening angle to 90
- Reducing the appliance door panel thickness by changing the design / using a stainless steel version (3/4 panel
thickness).
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DEPTH OF INSTALLATION CAVITY (Niche depth) As previously

By admin on November 12th, 2007

DEPTH OF INSTALLATION CAVITY (Niche depth)

As previously described, the required depth of the installation cavity is mainly dependent on the kitchen design.

The FREEDOM COLLECTION refrigeration columns are designed for a niche depth of 24 (610mm). So, if the kitchen

cabinet (case + face frame) is 24 deep, this should accommodate many standard installations.
Please be advised that additional depth may be required for kitchen designs intending the look of flush fascia
across the cabinetry and the refrigerator door panel.
A) Standard Overlay Design
On a kitchen with standard overlay cabinetry, the face frame is also an important part of the
design. If the same aesthetics are to be continued on the refrigerator, then not only the door
cabinetry panel thickness (e.g. ) is included, additionally the face frame thickness must be
emulated. Thereby the resulting thickness of the appliance door panel is + = 1
(face frame emulation+door panel = custom appliance door panel). This cumulative
appliance door panel
thickness of the resulting custom appliance door panel requires added depth for the
(emulating a face frame)
installation cavity. Example 24 + = 24 (recommended is 25 ).
B) Full Overlay Design
The above mentioned requirements are of course also valid for kitchens with full overlay
design. However there are some chances to work with a niche depth of 24 : For this, the
small remaining visible area of the fully overlaid face frame has to be emulated within the
standard appliance door panel thickness of . This can be done by simply ignoring the
visible area of the face frame on the refrigerator ( extended size of the appliance door
appliance door panel with nose
panel) or by emulating the face frame by creating a respective nose on the appliance door
(emulating a face frame)
panel (see sketch).