Interior Design
Lecture 08 # Interior Environmental Systems
Interior Environmental Systems
Interior environmental systems are essential components of any building. They
provide the thermal, visual, auditory, and sanitary conditions necessary for the
comfort and convenience of the building’s occupants. These systems must be
designed and laid out well to function properly. They must also be coordinated
with a building’s structural system. This requires the knowledge and expertise of
professional engineers and architects. Nevertheless, the interior designer should
be aware that these systems exist and know how they affect the quality of the
interior environment.
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Interior Environmental Systems
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Interior Environmental Systems
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Interior Environmental Systems
While the nature of a building’s structural system can manifest itself in its interior
spaces, the often complex networks of its mechanical and electrical systems are
normally hidden from view. Interior designers, however, should be aware of the
visible items that directly affect the interior environment, such as lighting
fixtures, electrical outlets, plumbing fixtures, and air supply registers and return
grills. Also of interest are the space requirements for horizontal and vertical runs
of air ducts and electrical and plumbing lines.
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Interior Environmental Systems
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Thermal Comfort
Thermal comfort is achieved when the human body is able to dissipate the heat
and moisture it produces by metabolic action, to maintain a stable, normal body
temperature.
Modes of Heat Transfer
Radiation: Heat energy is emitted by a warm body, transmitted through an
intervening space, and absorbed by a cooler body; radiant heat is not affected by
air motion or temperature.
Convection: Transfer is due to the circulatory motion of the heated parts of a liquid
or gas.
Conduction: Direct transfer occurs from the warmer to the cooler particles of a
medium or of two bodies in direct contact.
Evaporation: Heat loss is due to the process of converting moisture into a vapor.
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Thermal Comfort
Thermal comfort is dependent not only on air temperature but also on relative air
humidity, the radiant temperature of surrounding surfaces, air motion, and air
purity. To achieve and maintain thermal comfort, a reasonable balance must be
reached among these factors.
• The higher the mean radiant temperature of a room’s surfaces, the cooler the
air temperature should be.
• The higher the relative humidity of a space, the lower the air temperature
should be.
• The cooler the moving air stream, the less velocity it should have.
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Thermal Comfort
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Indoor Air Quality
Indoor air-quality considerations affect the type of heating, ventilating, and air-
conditioning (HVAC) equipment chosen to control air pressure and provide fresh
and conditioned air to the interior spaces of a building. Equipment maintenance
also affects the quality of air delivered, because molds and viruses thrive in warm,
moist equipment. Filters must be changed often to capture particulates effectively.
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Indoor Air Quality
Some interior design materials may release volatile organic compounds (VOCs)
that may irritate eyes, skin, and respiratory systems. Examples include:
• Formaldehyde in pressed wood products such as particleboard and plywood;
products are available without it. If used, seal all surfaces and edges.
• Some carpets and carpet pads and adhesives contain VOCs; select products
without them, or provide an off-gassing period after installation.
• Vinyl sheet flooring and wallcoverings owe their flexibility to petroleum-based
plasticizers; seek alternative products.
• Paints, stains, and other coatings have VOC levels printed on their labels; select
those with lower levels, and ventilate spaces where they are used.
• Some treated fabrics and modular office partitions contain VOC-producing
chemicals; provide an off gassing period if used.
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Ventilation
Buildings need a source of fresh air to replenish the oxygen used by the people
and equipment inside and to remove carbon dioxide and other wastes from the
air. Buildings designed without operable windows limit the intake of fresh air.
Increasing natural ventilation and air distribution is the most energy-efficient and
cost-effective way to freshen the air inside most buildings.
Air flows through a building because it moves from higher-pressure to lower-
pressure areas. Natural ventilation requires:
• A source of air having an acceptable temperature, moisture content, and
cleanliness
• A force—usually wind or thermal convection—to move the air through the
inhabited spaces of the building
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Ventilation
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Ventilation
Mechanical systems use fans to move air in and out of buildings, and incorporate
controls for regulating the volume, velocity, and direction of airflow. Blowers and
fans move the air through ductwork that delivers it to the building’s rooms.
Registers control the flow of air into interior spaces. Return air grilles take in used
air to be cleaned and reused or exhausted from the building.
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Ventilation
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Heating Systems
The primary objective of a heating system is to replace the heat lost within an
interior space. The basic heating system consists of a heat-producing medium,
equipment to convert the medium to heat, a means to deliver the heat to a
space, and, finally, a method for distributing the heat within the space.
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Heating Systems
Forced-Air Heating
Forced-air heating is a system that uses air heated in a gas, oil, or electric furnace
and distributed by a fan through ductwork to registers or diffusers in inhabited
spaces. The ductwork used for forced-air heating is often concealed by a
suspended ceiling; it may also be left exposed or be hidden in a soffit or other
interior construction. The locations of ducts and their associated grills and
registers will affect the appearance of the ceiling, and should be coordinated
with the locations of lighting fixtures, fire-suppression sprinklers, speakers, and
other ceiling equipment. Interior designers should collaborate with architects and
engineers to ensure a coordinated and attractive ceiling design.
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Heating Systems
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Heating Systems
Solar Heating
The amount of sunlight falling on a building typically has enough energy to keep it
comfortable throughout the year. Most solar-heating systems can accommodate
40 to 70 percent of a building’s heating load.
A passive solar-heating system incorporates solar collection, storage, and
distribution into a building’s architectural design, with minimal use of pumps or
fans. This is accomplished by carefully siting the building and designing the size
and type of windows, as well as by using massive materials that can store thermal
energy. Overhangs and shading devices are used to avoid glare and overheating.
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Heating Systems
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Heating Systems
Active solar-heating systems use pumps, fans, heat pumps, and other mechanical
equipment to transmit and distribute thermal energy via air or a liquid. They
offer better control of the interior environment than passive systems, and can be
added onto most existing buildings. Most active systems are operated by
electricity.
Many buildings use hybrid systems with passive-solar design features
supplemented by electrically driven fans or pumps.
Even an interior that is not designed specifically for solar heating can take
advantage of this free heat source in cold weather by absorbing the sun’s warmth
through windows during the day, and blocking its exit with thermal window
treatments at night.
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Heating Systems
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Heating Systems
Hot-Water Heating
Hot-water or hydronic heating is a system for heating by means of water heated in
a boiler and circulated by a pump through pipes to radiators or convectors. Steam
heating is similar in principle, utilizing steam generated in a boiler and circulating it
through piping to radiators.
Radiant Heating
Radiant heating systems utilize heated ceilings, floors, and sometimes walls as
radiating surfaces. The heat source may be pipes or tubing carrying hot water, or
electric-resistance heating cables embedded within the ceiling, floor, or wall
construction.
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Heating Systems
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Heating Systems
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Air Conditioning
An air conditioner is usually considered to be a means for supplying cooled air. A
true air-conditioning system, however, provides all-year climate control by
treating air in multiple ways to ensure the thermal comfort of a building’s
inhabitants. An air-conditioning system can regulate not only air temperature but
also relative air humidity, air motion, and air purity.
While the architect and engineers plan a heating or air-conditioning system
during the design of a building, the interior designer can affect the final result
through the selection of wall, window, and floor coverings and by the adjustment
of airflow patterns. Air-conditioning is very energy intensive, so strategies that
keep unwanted heat out, such as shading, and those that help air move through a
space, such as careful placement of furnishings and the installation of ceiling fans,
support energy conservation.
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Air Conditioning
Air-Conditioning Systems:
• Bring in outside air and mix it with a limited amount of filtered return air.
• Add or remove heat and water vapor to control air temperature and humidity.
• Deliver the conditioned air to the building’s interior spaces.
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Air Conditioning
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Under Floor Air Distribution
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Under Floor Air Distribution
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