1. Link to Passipedia
2. Link to Energieeffizienz
Air Changes per Hour (ACH)
ACH is an acronym for Air Changes per Hour and is a
measurement of air infiltration. It is the total volume of air in a home that
is turned over in one hour. Tightly constructed homes may have an ACH of 0.35
to 0.25 or less. A typically built new home may have an ACH of around 1.75 ACH.
Older, poorly weatherstripped and air-sealed homes may have higher than
2.5 ACH.See also Blower-door below for how to test for ACH.
Air Flow (CFM)
CFM50 is defined as the air flow (in cubic feet per
minute) needed to create a 50 Pascal pressure change in the building
envelope.CFM50 is one of the most basic measurements of airtightness. Air flow
measurements are sometimes referenced to different building pressures such as
25 or 50 Pascals, with 50 being most common.
Air-sealing is the practice of filling gaps, holes,
or cracks in a builidng's envelope in an effort to tighten the home's pressure
boundary. Air sealing is one of the most significant energy efficiency
improvements you can make to your home. Air sealing will not just reduce
energy costs, it will also improve your home's comfort and durability. Some
common air-sealing products include latex or silicone caulk, expanding foam products,
weatherstripping, and even dense-packed cellullose in exterior walls.
A diagnostic tool designed to measure the
airtightness of buildings and to help locate air leakage sites. A blower door
consists of a calibrated fan for measuring an air flow rate and a pressure
sensing device to measure the pressure created by the fan flow. The combination
of pressure and fan flow measurements are used to determine the building
airtightness. The airtightness of a building is useful knowledge when trying to
increase energy conservation or decrease indoor air pollution or control
The Minneapolis Blower Door has long been
recognized as the best designed and supported building airtightness testing
system in the world. Combined with specialized accessories and testing
procedures developed by The Energy Conservatory, the Minneapolis Blower Door is
the system of choice for utility DSM programs, energy raters, HVAC contractors
and weatherization professionals.
The separation between the interior and the
exterior environments of a building. It serves as the outer shell to protect
the indoor environment as well as to facilitate its climate control. The
red outline in the picture below follows the building envelope, also referred
to as the pressure boundary.
Building performance is a set of measurable
building characteristics including:
Indoor Air Quality
Building science is the collection of scientific
knowledge that focuses on the analysis and control of the physical phenomena
affecting buildings. This includes the detailed analysis of building materials
and building envelope systems. The practical purpose of building science is to
provide predictive capability to optimize building performance and understand
or prevent building failures.
Built-Up-Roof Systems (BURs)
A roof consisting of multiple plies of roof felts
laminated together with bitumen. Built-up roof material can consist of
bitumen-saturated felt, coated felt, polyester felt or other fabrics. A
surfacing is generally applied and can be asphalt, aggregate (gravel or slag),
emulsion or a granule-surfaced cap sheet.
This section was written simply to give people an
idea of what a Built-Up Roof (B.U.R. for short) is and how it’s put together.
The materials and information listed here are not comprehensive nor do they
represent all types of built-up roof materials available.
Built-Up Roofing is one of the oldest ways of
installing a new roof. It was first known as composition roofing and started in
the 1840's. B.U.R.’s come in two basic types, asphalt and coal tar, and three
basic components – (1) the waterproofing component, (2) the reinforcing
component, and (3) the surfacing component which is used to protect the other
components from the elements.
Unfortunately, most BUR systems are not installed
perfectly, and many leakage problems have been commonly found as a
In physics, buoyancy is the upward force on an
object produced by the surrounding liquid or gas in which it is fully or
partially immersed, due to the pressure difference of the fluid between the top
and bottom of the object.
Cellulose insulation is a natural product made
primarily of recycled newspaper, which is mixed with borates that provide it
with excellent fire-retardant, mold & mildew retardant, and insect/rodent
retardant properties. Cellulose insulation has a high R-value per inch
installed (3.6-3.8), and is one of the "greenest" insulation products
Cellulose can be blown into attics, referred to as
"loose-fill", and sprayed into empty wall cavities in existing homes
and new construction with different application methods.
For existing homes there are two methods for
installing cellulose in exterior walls. The older, traditional method is
called the "low-density" or "two-hole" method. This
technique has been around for decades and is the most widely practiced
application method, however there are serious drawbacks to this technique,
mainly settling of the insulation due to its low-density.
Low-density method, and
Dense-packing (high-density method)
In order to compare the relative airtightness of
buildings, it is useful to normalize the measurements for the size of the
building. This allows easy comparison of various sized buildings to each other,
or to program guidelines.
One of the most common ways to normalize building
airtightness is to calculate the number of times per hour that the total volume
of the enclosure is changed, when the enclosure is subjected to a 50 Pascal
pressure difference. To calculate air changes per hour, the total volume of the
enclosure is required in addition to the CFM50 measurement. It is also common
to use the building enclosure surface area to normalize airtightness
A pressure of 50 Pa is equal to 0.2 inches of
The newer, more effective method for insulating an
existing home that doesn't have any wall insulation is called
"dense-packing" or the "tube-in method".
Dense-packing requires a slightly different procedure for filling the
wall cavities than the low-density method and takes a little longer to
complete, however the benefits are significant and long-lasting.
Instead of drilling two one-inch holes per cavity,
the installer drills only one two-inch or larger hole about three feet from the
bottom of the wall and inserts a smaller, flexible tube into the cavity, which
runs all the way to the top of the wall. The insulation is then installed
with the tube inside the wall and is removed slowly once the material stops
packing, completely filling the wall cavity without any gaps or voids. This
higher-density method will never settled when done correctly and also provides
a very effective air-barrier to outside air infiltration as well.
Digital pressure gauge
A pressure gauge, in terms of building performance
diagnostics, is a testing device that reads air pressure in terms of Pacals
(Pa) or inches of water collumn (w.c.), as well as air flow in cubic feet per
The Energy Conservatory sells an excellent digital
pressure gauge called the DG700.
The ability to maintain satisfactory aesthetic,
economic, and functional performance for the useful life of the structure.
The more durable a structure is, the longer its functional life will be.
Energy efficiency is using less energy to provide
the same level of energy service. An example would be insulating a home to use
less heating and cooling energy to achieve the same temperature. Another
example would be installing fluorescent lights and/or skylights instead of
incandescent lights to attain the same level of illumination. Efficient energy
use is achieved primarily by means of a more efficient technology or process
rather than by changes in individual behaviour.
Fiberglass insulation is what most people think of
when they refer to insulation materials. The "Pink Panther"
brand comes to mind....Ownens Corning. To this day most of the new homes
and buildings are built using fiberglass "batts" or rolls.
Over the years, however, building-science R&D
has shown how poor of an insulating material fiberglass can be, if not
installed perfectly. It is extrememely difficult to install perfectly, as
bending, twisting, or compressing the material reduces the R-value significantly,
and if the exterior membrane of the building envelope is not air-sealed well,
then that air movement will virtually eliminate any potential insulating power.
Green building is the practice of increasing the
efficiency with which buildings use resources — energy, water, and materials —
while reducing building impacts on human health and the environment, through
better siting, design, construction, operation, maintenance, and removal — the
complete building life cycle.
A similar concept is natural building, which is
usually on a smaller scale and tends to focus on the use of natural materials
that are available locally. Other commonly used terms include sustainable
design and green architecture.
The related concepts of sustainable development and
sustainability are integral to green building. Effective green building can
lead to 1) reduced operating costs by increasing productivity and using less
energy and water, 2) improved public and occupant health due to improved indoor
air quality, and 3) reduced environmental impacts by, for example, lessening
storm water runoff and the heat island effect.
Practitioners of green building often seek to
achieve not only ecological but aesthetic harmony between a structure and its
surrounding natural and built environment, although the appearance and style of
sustainable buildings is not necessarily distinguishable from their less
Indoor Air Quality
(IAQ) deals with the content of interior air that
could affect the health and comfort of building occupants. The IAQ may be
compromised by microbial contaminants (mold, bacteria), chemicals (such as
carbon monoxide, radon), allergens, or any mass or energy stressor that can
induce health effects.
Recent findings have demonstrated that indoor air
is often more polluted than outdoor air (albeit with different pollutants)
although this has not changed the common understanding of air pollution. In
fact, indoor air is often a greater health hazard than the corresponding
outdoor setting. Using ventilation to dilute contaminants, filtration, and
source control are the primary methods for improving indoor air quality in most
Infiltration is the unintentional or accidential
introduction of outside air into a building, typically through cracks in the
building envelope and through use of doors for passage. Infiltration is
sometimes called air leakage.
Infiltration is caused by wind, building
pressurization and by air buoyancy forces known commonly as the stack effect.
Infrared Thermography, thermal imaging, or thermal
video, is a type of infrared imaging science. Thermographic cameras detect
radiation in the infrared range of the electromagnetic spectrum (roughly
900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation.
Since infrared radiation is emitted by all objects
based on their temperatures, according to the black body radiation law,
thermography makes it possible to "see" one's environment with or
without visible illumination. The amount of radiation emitted by an object
increases with temperature, therefore thermography allows one to see variations
in temperature (hence the name).
When viewed by thermographic camera, warm objects
stand out well against cooler backgrounds; humans and other warm-blooded
animals become easily visible against the environment, day or night. As a
result, thermography's extensive use can historically be ascribed to the
military and security services.
Insulation in buildings is an important factor to
achieving thermal comfort for its occupants. Insulation reduces unwanted heat
loss or gain and can decrease the energy demands of heating and cooling
systems. It does not necessarily deal with issues of adequate ventilation and
may or may not affect the level of sound insulation.
In a narrow sense insulation can just refer to the
insulation materials employed to slow heat loss, such as: cellulose,
fiberglass, rock wool, polystyrene, urethane foam, vermiculite But it can also
involve a range of designs and techniques to address the main modes of heat
transfer - conduction, radiation and convection materials., and earth or
The effectiveness of insulation is commonly
evaluated by its R-value. However, an R-value does not take into account the
quality of construction or local environmental factors for each building.
Construction quality issues include inadequate vapour barriers, and problems
Leakage area estimates are a useful way to
visualize the cumulative size of all leaks or holes in the building enclosure.
Estimated leakage areas can also be used in infiltration models to estimate
natural infiltration rates (i.e. the air change rate under natural weather conditions).
In order to accurately estimate leakage areas, it
is best to conduct the blower door test over a wide range of building pressures
(e.g. 60 Pa to 15 Pa). There are a variety of standard calculation methods used
to calculate leakage areas.
When a contractor retro-fits an existing house with
cellulose using the low-density method, they typically drill two one-inch
diameter holes per wall cavity; one about three feet from the bottom and
another about one foot from the top. The bottom hole is filled first and
continues to fill until the material flow stops. The top hole is then
filled to finish the channel.
The inherant problem with this method is its
low-density installation and the fact that air pockets form within the wall
cavity when this method is used. Once the air in these pockets dissapate
from the wall cavity, the entire channel of insulation sags or settles, greatly
reducing the effectiveness of the installation, as well as any air-sealing
benefits the homeowner was seeking to achieve.
Because of these problems, the dense-pack method
Moisture management refers to the active planning
of how rainwater is collected and directed away from a building, so as to avoid
any potential negative effects.
Regardless of project location or building type,
the goal of a successful building design is to keep water out and provide
thermal control within the interior spaces.
When moisture infiltrates the building envelope,
several undesirable conditions can occur, including mold and mildew, structural
steel corrosion, and rotting wood. These conditions can result in high energy
costs, ongoing maintenance problems, compromised indoor air quality, and
failure of one or more architectural and engineering building systems. If they
are not adequately addressed, the problems caused by moisture infiltration can
potentially increase risk and liability concerns for architects, design
professionals, building owners, and building occupants.
Simply put, a pascal is a unit of pressure
measurement used most often in building diagnostics when testing for duct
leakage, pressure differentials, etc.
The Wikipedia definition is much more complicated
The pascal (symbol: Pa) is the SI derived unit of
pressure or stress (also: Young's modulus and tensile strength). It is a
measure of perpendicular force per unit area i.e. equivalent to one newton per
square meter or one joule per cubic meter. In everyday life, the pascal is
perhaps best known from meteorological air-pressure reports, where it occurs in
the form of kilopascal (1 kPa = 1000 Pa).
Often more commonly referred to as walls, ceilings,
floors, and foundation walls. Depending on how the HVAC system is
designed and the construction style of the house, the pressure boundary
generally encompasses all of the heated and cooled (conditioned) areas of the
building, although it is often mis-placed in older homes, resulting in
excessive heat loss and gain.
In order for the pressure boundary to function
properly, it must be a continuous and uniform surface throughout, and be
aligned exactly with the thermal boundary (insulation) in the building.
As you can see in the picture below, a mis-aligned
or "open" pressure boundary can lead to outside air infiltration,
degradation of insulation quality and R-value, and excessive heat loss, and
high utility bills.
The pressure pan is a duct leakage diagnostic tool
which is used along with the Blower Door and digital pressure gauge to identify
exterior air leakage in duct systems. This technique involves placing a
gasketed pressure pan over each register or grille with the furnace air handler
fan off and the Blower Door depressurizing the house to a standard reference
The lower the pressure number found on the digital
pressure gauge, the "tighter" the duct run is. For example, a
duct pressure reading of -0.5 is much tighter than -3.0. Typically a
pressure number less than -3.0Pa is considered "tight", while
anything higher is in need of duct-sealing.
A measurement of the pressure between a duct run
and the room where the duct register or grille is located provides a quick and
reliable indication of whether significant exterior duct leaks exist in that
section of the duct system.
Stack effect is the movement of air into and out of
buildings, and is driven by buoyancy.
Since buildings are not totally sealed (at the very
minimum, there is always a ground level entrance), the stack effect will cause
air infiltration. During the heating season, the warmer indoor air rises up
through the building and escapes at the top either through open windows,
ventilation openings, or leakage. The rising warm air reduces the pressure in
the base of the building, forcing cold air to infiltrate through either open
doors, windows, or other openings and leakage. During the cooling season, the
stack effect is reversed, but is typically weaker due to lower temperature
Also referred to as "green building", is
the practice of increasing the efficiency with which buildings use resources —
energy, water, and materials — while reducing building impacts on human health
and the environment, through better siting, design, construction, operation,
maintenance, and removal — the complete building life cycle.
Human thermal comfort is defined by ASHRAE as the
state of mind that expresses satisfaction with the surrounding environment
(ASHRAE Standard 55). Maintaining thermal comfort for occupants of buildings or
other enclosures is one of the important goals of HVAC design engineers.
Thermal comfort is affected by heat conduction,
convection, radiation and evaporative heat loss. Thermal comfort is maintained
when the heat generated by human metabolism is allowed to dissipate thus
maintaining thermal equilibrium with the surroundings. Any heat gain or loss
beyond this generates a sensation of discomfort.
It has been long recognized that the sensation of
feeling hot or cold is not just dependent on air temperature alone