The EnerGuide Housing Glossary – Definitions

Terms

The EnerGuide Housing Glossary – B

Bagged System of insulation

See Keeping The Heat In - Chapter 6: Basement insulation: 6.4 Open Foundations

Baseboards

See - Keeping The Heat In - Chapter 4: Comprehensive air leakage control: 4.2.5 Tips on sealing some of the leakiest areas - Trim areas

Basement Header – see “Header”

 

Basement header space – see “Header space”

 

Basement Slab

A slab is a single layer of concrete, several inches thick. A rigid, horizontal (or almost horizontal) concrete structure with a large horizontal surface in relation to its thickness, used as the foundation of a house.

Read more about foundations in Keeping The Heat In - Chapter 6: Basement insulation

Batt Insulation / Batt / Batts / R-12 Batt

Pre-cut, glass fibre, mineral wool or other fibrous insulating material, of varying thicknesses and densities, sized to fit between framing members.

Read more about batt insulation and other insulation types in Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Batt or blanket insulation

Below Grade Area

Any part of a structure or site feature that is below the adjacent finished ground level. Read more about above and below grade areas in Keeping The Heat In - Chapter 6: Basement insulation

Blanket Type Insulation

A flexible type of pre-cut, glass fibre, mineral wool or other fibrous insulation, formed into sheets or rolls of varying thicknesses and densities, usually with a vapor-barrier on one side and with or without a container sheet on the other side, and sized to fit between framing members.

Read more about insulation types in Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types

Blower Door Test

Energy advisors and other trained professionals use blower door test equipment to measure your home's rate of air leakage (otherwise known as air tightness). The blower door is a variable-speed fan mounted on an adjustable panel that can fit into an exterior door opening of your home.

As part of the EnerGuide Rating System, the blower door test is performed and the results of the test are incorporated into the rating and the house label.

What are the steps to run the Blower Door test?

  1. When the fan is turned on, the pressure inside your home is gradually reduced to allow outside air to flow into the house through unsealed openings or cracks in the house structure.
  2. Pressure gauges connected to the fan measure the rate of airflow required to keep your home at a constant pressure so that the advisor can calculate your home's resistance to air infiltration.
  3. The blower door test equipment then calculates the air leakage rate of the home. The results of the test are considered in your home's energy efficiency rating. Because airtight homes are energy efficient, a house that has little air leakage will score a better rating than a home that has a lot of air leakage.
     
Boiler System [Hydronic System]

A gas-fired (natural gas or propane) hydronic heating system consists of a boiler that heats water. The hot water is then piped to convective heaters, such as cast-iron radiators; baseboard and cabinet heaters; a piping system that runs through the floor or ceiling; or fan-assisted coils.

The energy-efficiency performance of a gas- or propane-fired boiler over a heating season is called the Annual Fuel Utilization Efficiency (AFUE). The AFUE is expressed as a percentage, where the higher the percentage, the greater the efficiency.

Some condensing gas boilers have sealed combustion systems that draw their combustion air from, and vent the exhaust gases directly to, the outside. This system reduces heat loss and unwanted drafts, and can greatly reduce the risk of back-drafting or the spillage of combustion gases into the home.

Bottom or Top Plate

A horizontal structural member attached to the tops and bottoms of wood stud walls.

Box beam – see “Header”

 

Building Envelope

The exterior surface of a building that separates the indoor heated air from outdoor air.

Building Paper

A heavy paper usually impregnated with bitumen and applied under or behind exterior finish materials in wood-frame construction to protect the assembly from liquid water.

The EnerGuide Housing Glossary – C

Canadian Geoexchange Coalition (CGC)

See http://www.geo-exchange.ca/en/

Canadian Solar Industries Association (CANSIA)

See www.cansia.ca

Canadian Standards Association (CSA)

See http://www.csagroup.org/ca/en/services/codes-and-standards

Canadian Wind Energy Association (CANWEA)

See www.canwea.ca

Cathedral Ceiling

A ceiling that is inclined, typically sloping up to the centre of the room. The ceiling may follow the roof slope (e.g. in the case of a rafter ceiling) or may have a slope that differs from the roof slope (e.g. in the case of a scissor truss).

Caulking

See Keeping The Heat In - Chapter 3: Materials: 3.3.2 Sealants

Ceilings

The overhead inside surfaces of a room.

Chimneys

See Keeping The Heat In - Chapter 4: Comprehensive air leakage control: Figure 4-2 Typical Leakage areas.

Coefficient Of Performance (COP)

A measure of the efficiency of a heat pump or air-conditioning equipment. It is the ratio of input energy to output energy. A device that has an energy input of 1 kW and an output of 3 kW, will have a C.O.P. of 3.

Combination Systems

A system that provides both domestic hot water and space heating using potable water as the space-heating working fluid. This is distinct from a boiler-based system that may also provide space and domestic hot water heating, but the working fluid for space-heating is contained in a closed loop and is not potable.

Condensation

See Keeping The Heat In - Chapter 2: How your house works: 2.1.6 Condensation

Condensing Gas Furnace / Condensing gas-fired furnace

Condensing gas furnaces are the most energy-efficient furnaces available. They have additional heat exchange surfaces made of corrosion-resistant materials that extract heat from the combustion by-products before they are exhausted. In the condensing heat exchange section, combustion gases are cooled to a point at which the water vapour condenses, thus releasing additional heat into the furnace. The condensate is piped to a floor drain or condensate pump.

A chimney is not needed because the flue gas temperature is so low that the gases are vented out of the house through an approved plastic pipe.

Condensing tank-type hot water heater

High-efficiency, condensing, storage-type water heaters have a specially designed heat exchanger that, in gas (natural gas or propane) models, recovers heat from the water vapour in the combustion gases. This feature along with electronic ignition, sealed combustion, increased tank insulation and factory-installed heat traps, contribute to high efficiency levels. Condensing water heaters are not required to be vented to a chimney and require a plumbing drain or condensate pump to remove the collected condensate.

Although more common in commercial installations, a high-efficiency condensing, storage-type gas water heater is a good choice for households with a high demand for hot water. In some cases, these heaters can be used to provide both space and water heating (i.e., combination systems).

Cooling

See Space Cooling.

Cooling Load
Crawl Space Insulation

See Keeping The Heat In - Chapter 6: Basement insulation: 6.3 Crawl Spaces

Crawlspace

A low-clearance space between the lowest occupied floor of a house and the ground or slab-on-ground beneath.

The EnerGuide Housing Glossary – D

Dense-Pack Fibre Insulation

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types: Loose-fill insulation, Cellulose fibre

Design Heating / Cooling Load

Design heating/cooling load values give an estimate of the capacity of the heating and cooling equipment needed to maintain your home at 22 °C in the winter and 24 °C in the summer and are provided for guidance only. Before having a new heating/cooling system installed, your heating/cooling contractor should perform an independent, detailed heat loss/heat gain calculation on your home in order to select the appropriate equipment.

Direct Current (DC) Fan Motor

Modern furnaces are often equipped with high efficiency, direct current (DC) fan motors that consume considerably less electricity than standard alternating current (AC) motors. High efficiency motors are also sometimes referred to as DC brushless motors

Domestic Hot Water System / Domestic Water Heater / Water heating

See Keeping The Heat In - Chapter 9: Operating your house - 9.2 Domestic Hot Water

Double-Glazed Sliding Doors

A sliding door that contains a window made of two layers of glass separated by an air space to increase its thermal resistance (RSI), or, equivalently, decrease its U-value.

Drain Water Heat Recovery System

Drain water heat recovery is a simple technology to save on energy used to heat water. This system takes advantage of the warm water flowing down the drains to preheat the water going into the hot water tank. Preheating the water reduces the amount of energy needed to heat the water to the set temperature. A study by the Canadian Centre of Housing Technology stipulates that drain water heat recovery pipes are most effective when you have large “drain water events”, where a lot of warm water is being drained, mostly from the shower, sink, clothes washer and dishwasher.

Drywall

A panel product, also known as gypsum board, made from gypsum plaster with a paper covering on the front and back and used as a finish material on interior walls and ceilings.

Ductless mini-split heat pump

Ductless mini-split heat pumps are heating and cooling systems that can be ideal for retrofit in homes with hydronic or electric resistance baseboard heating. They are wall-mounted, free-air delivery units that can be installed in individual rooms of a house. Up to eight separate indoor wall-mounted units can be served by one outdoor section. See also air source heat pump.

Ducts

Keeping The Heat In - Chapter 5: Roofs and attics: 5.1.3 Air sealing

Ductwork

A system of conduits, or ducts, that conveys air through a house in space heating, air conditioning and ventilation systems.

Improperly designed ductwork can create comfort problems, such as rooms that are too hot or too cold due to an inconsistent flow of air throughout the house.

The EnerGuide Housing Glossary – E

Earth-Energy System

An earth-energy system uses earth or ground water or both as the sources of heat in the winter, and as the "sink" for heat removed from the home in the summer. Earth-energy systems can be used with forced-air and hydronic (hot water) space heating systems and for pre-heating domestic hot water.

Some earth-energy systems are ENERGY STAR qualified.

The heating and cooling efficiency ratings for earth-energy systems use different terminology. For example, the heating rating is the coefficient of performance (COP) and the cooling rating is the energy efficiency ratio (EER). The higher the ratings, the more energy efficient the earth-energy system.

Some earth-energy systems are ENERGY STAR qualified.

Edge Spacer

A spacer bar is placed around the edge of the glass in an insulated glazing (IG) unit to hold the panes apart. The spacer bar also has a desiccant in it to absorb all the moisture remaining inside the glazing unit after it had been sealed. This prevents fogging between the panes.

Effective RSI

Effective RSI-value (R-value) of assembly (post-construction) represents the resistance to the flow of heat of the entire wall, ceiling or floor assembly considering the structure, insulation, framing, sheathing and all finishing. Typically this value is lower than the nominal RSI-value (R-value) of the insulation because the framing material has a lower RSI-value (R-value) than the insulation.

Electric baseboard heater

A thin linear heating appliance that has openings at the top and bottom through which air circulates and collects heat from an internal electric heating element. Typically installed at the base of exterior walls under windows.

Electric baseboard heaters rely on the natural convention of heated air to distribute heat. These units are available in different lengths, suitable to the heating requirements of a room.

Electric baseboard heaters consume a lot of electricity. Each baseboard heater normally requires its own dedicated electric circuit. The easy installation of this wiring is a factor in evaluating the cost of the system. In newly constructed structures or buildings, baseboard heating usually has the lowest initial cost compared to other systems, but often has very high operating costs.

Electric Furnace

Electric furnace forced-air systems come in a wide range of capacities generally from 10 kW to 50 kW. The heating elements, circulation fan, air filter, and control devices are contained in a compact cabinet.

If electricity is your only energy source, unused chimney flues can be closed off, insulated, and sealed. Closing off the chimney flues can have an effect on drafts and humidity levels in the house, and will reduce heat loss.

Energy Advisor

Energy advisors, sometimes known as EnerGuide rating service energy advisors are independent experts in energy efficiency for homes. They are affiliated with professional organizations across the country that work with Natural Resources Canada to deliver the EnerGuide Rating System in your area.

Energy Efficiency Ratio (EER)

The Energy Efficiency Ratio (EER) is a method of reporting the energy performance of air-to-air heat pumps. The higher the EER, the more efficient the equipment is.

Energy Factor (EF)

Energy Factor is a value which measures the energy efficiency of water heaters and considers off-cycle and other losses in addition to steady-state efficiency.

The efficiency of fuel-fired domestic hot water equipment is expressed as the energy factor (EF) or thermal efficiency. The higher the number, the more efficient the water heater.

The efficiency of electric domestic hot water equipment is expressed in Watts of standby loss, where the lower the number, the more efficient the water heater.

Energy Recovery Ventilator (ERV)

An energy recovery ventilator (ERV) is an energy-efficient, central ventilation system similar to a heat recovery ventilator (HRV).

A balanced-flow ERV recovers heat from exhausted air, but in comparison to an HRV, it does not remove as much moisture from the house. These features are recommended where cooling load demand is high or where the relative humidity (i.e. humidity level) tends to be on the low side (e.g. in northern Canada). Thus, an ERV can help to keep the house from drying out.

Read more about ERVs and HRVs in Keeping The Heat In - Chapter 9: Operating your house: 9.4.5 Heat recovery ventilators and energy recovery ventilators

ENERGY STAR

ENERGY STAR® is the mark of high-efficiency products in Canada. The familiar symbol makes it easy to identify the best energy performers on the market.

ENERGY STAR qualified products such as home heating and cooling equipment meet strict technical specifications for energy performance—tested and certified.

They save energy without compromising performance in any way. Typically, an ENERGY STAR qualified product is in the top 15 to 30 percent of its class for energy performance. Saving energy saves you money and reduces your impact on the environment.

The ENERGY STAR Initiative is a voluntary partnership between the Government of Canada and industry to make high efficiency products readily available and visible to Canadians. Canada is an international partner in the U.S. ENERGY STAR program.

NRCan formally enrolls manufacturers, retailers and other organizations as Participants in the ENERGY STAR Initiative. Participants help promote ENERGY STAR and ensure ENERGY STAR qualified products are prominent and readily available in the marketplace and to Canadian consumers.

Find out more about ENERGY STAR for home equipment.

Find out more about ENERGY STAR for New Homes.

ENERGY STAR for New Homes

The ENERGY STAR® for New Homes initiative promotes energy efficiency guidelines that enable new homes to be approximately 20 percent more energy efficient than a typical new home. The increased efficiency of these homes translates into reduced energy costs for homeowners. This initiative is also designed to encourage energy-efficient practices that help reduce greenhouse gas emissions. By identifying and promoting energy-saving products, the initiative helps protect the environment and lowers energy bills at the same time.

An ENERGY STAR qualified new home is a home that has been built by a licensed ENERGY STAR® for New Homes builder who incorporates energy efficient features into the home so it can meet the ENERGY STAR® for New Homes technical specifications.

Find out more about ENERGY STAR for New Homes.

Environmental Protection Agency

See www.epa.gov

Equivalent Leakage Area (ELA)

Equivalent leakage area is another way of describing the airtightness of the building envelope. It represents the size of a single hole in your building envelope if all the individual air leakage holes or gaps were added together. The smaller the equivalent leakage area, the less energy you will need to control the temperature of your home (but you will still need to ensure that you have adequate ventilation).

Exposed Floors / Open Foundation / Floors Over Unheated Space

Exposed floors and overhangs may occur, for example, at a bay window, at an overhanging floor or for a room over a garage.

Exterior Pipe Penetration

See Keeping The Heat In - Chapter 4: Comprehensive air leakage control: Figure 4-2 Typical Leakage areas

Exterior-Grade Caulking

See Keeping The Heat In - Chapter 3: Materials: 3.3.2 Sealants

Extruded Polystyrene

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types (Rigid board insulation and Extruded polystyrene)

The EnerGuide Housing Glossary – F

Fascia

An exterior, vertically positioned but horizontally running, trim member used to close and finish the outer exposed ends and faces of rafters and roof trusses. Fascia board may also support eavestroughing.

Flashing

Water-proof sheet or other material placed to prevent water penetration or to direct and shed the flow of water over and off of the building envelope or other element.

Foam Board / Foam Board Insulation

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types (Rigid board insulation)

Foam Sealant

See Keeping The Heat In - Chapter 3: Materials: Table 3-2 Air barrier caulking and sealants

Forced-air Heating Systems

A heating and/or cooling system that uses a motor-fan set to distribute heated air via a central ductwork system to the different rooms of a house to meet space conditioning needs. To accommodate different types of houses, there are three main furnace designs for use with forced-air systems. The designs are named according to the way air travels through the system.

  • Upflow furnaces are recommended for basement floor locations.
  • Horizontal flow furnaces are particularly suited for crawl space installations.
  • Downflow furnaces are recommended for installations in mobile homes or on the main floor of houses on concrete slabs.
     
Foundation

The base on which a house rests. A structure made of reinforced concrete, preserved wood, masonry, or steel that transfers loads (weight) from a house to the ground. It is designed to evenly distribute all loads that are transmitted to it through its footings to the underlying soil or rock.

Read more about foundations in Keeping The Heat In - Chapter 6: Basement insulation.

Foundation header – see “Header”

 

Foundation header space – see “Header space”

 

Frame Wall

Frame walls have a cavity that may be insulated. Different construction techniques determine the size of the cavity and ease of access from either the interior or exterior. The wall construction also affects details that can interfere with the insulation, including top and bottom plates, fire stops, blocking, plumbing, wiring and heating ducts. Using dense-pack insulation techniques, empty-cavity and some partially insulated cavity frame walls can be insulated from the top and bottom or from the interior or exterior. Insulating should include air sealing.

The EnerGuide Housing Glossary – G

Gasket

See Keeping The Heat In - Chapter 3: Materials: Figure 3-3 Electrical outlet gasket

Gigajoule (GJ)

A unit of energy in the Metric System. It can be used as a measure of any type of energy that is consumed or produced in your home. Specifically, one GJ is the equivalent of 278 kWh of electricity, 27m3 of natural gas, 26 L of oil, 39 L of propane, or 948,450 BTUs. One GJ is roughly equal to the energy from two standard barbeque propane tanks or 30 litres of gasoline in a car’s gas tank.

Glazing

Glazing is the generic term for the transparent material - usually glass - in a window, door or skylight. A single-glazed product has one pane of glass; a double-glazed product has two panes; a triple-glazed three; and a quad-glazed, four. A thin layer of suspended polyester film may be substituted for one of the panes inside a triple- or quad-glazed product to reduce the overall weight. In Canada, all windows, skylights and doors should be at least double-glazed.

GHGs – see “Greenhouse Gas (GHG) Emissions”

 

Greenhouse Gas (GHG) Emissions

The amounts of carbon dioxide, methane and nitrous oxide that are produced directly, by burning fossil fuels, or indirectly, through the consumption of electricity. Greenhouse gas emissions are expressed in carbon dioxide equivalent units (CO2). Greenhouse gas emissions are calculated by multiplying the quantity of fuel or electricity used in your home by the emission factors for the particular energy source. Electricity emission factors vary by province because there are different emissions associated with each province’s method of producing electricity. One tonne of greenhouse gas emissions is equivalent to the CO2 emissions produced by driving an average efficiency mid-sized vehicle from Toronto to Vancouver.

Read more about Canada's greenhouse gas emissions

The EnerGuide Housing Glossary – H

Hardware

High-quality hardware, such as cranks, handles, latches and locksets also help to provide a good air seal in windows and doors. They should be designed not to conduct heat through the product.

Also known as the 'header joist', the 'rim joist' or the 'box-beam', the header is the outermost member of a series of joists in the support structure of a floor, be it parallel, perpendicular or at any angle to the joists. Headers are also used to support joists around openings such as those for stairs or chimneys.

Read more about header joists inKeeping The Heat In - Chapter 6: Basement insulation: Figure 6-18 Reducing air leakage in the joist header area

Header joist – see “Header”

 

Header space

Also known as the ‘rim joist space’, or the ‘foundation header space’, this is the area where the floor joists are supported by the foundation walls in both basements and crawl spaces. It is the area where the house structure rests on the foundation. This area is prone to air leakage and is seldom properly insulated, resulting in unwanted drafts, dust and pollen entry and vermin access.

Health and Safety Considerations

See Keeping The Heat In - Chapter 1: Introduction: 1.4 Health and Safety Considerations

Heat Loss

The loss of heat from a building to outdoors through the transfer of energy by conduction, convection, radiation and mass transfer. Heat energy naturally moves from warmer areas to colder areas.

Conduction: heat energy moves through solid materials

Convection: heat is lost through the movement of air

Radiation: heat energy is absorbed by a building component then moves (radiates) toward the cooler side

Heat loss calculations are used to size space heating systems.
Heat Loss / Heat Gain Calculation

See Design Heating/Cooling Load

Heat Pump Hot Water Heater

Heat pump water heaters use electricity to transfer heat from the air instead of converting electricity directly to heat. Heat is taken from the air in the basement or utility room (or sometimes from outside) and transferred to a tank of water.

Heat pump water heaters remove heat and humidity from the air. As heat is removed from inside the home in summer, you will need less air conditioning. Heat pump water heaters are less advantageous in the winter when space heating is required.

Some heat pump hot water heaters can be added to a conventional hot water tank.

Heat Recovery Ventilator (HRV)

An energy-efficient HRV is one of the best ways to control indoor air quality. An HRV saves on energy costs compared to conventional ventilation systems because it recovers heat from exhausted air. The HRV exhausts stale air and passes it through a heat exchanger. The exchanger transfers the heat to the fresh incoming air before it exhausts the stale air to the outside. The HRV must be balanced to maximize performance and not affect the house pressure.

Read more about HRVs in Keeping The Heat In - Chapter 2: How your house works: 2.3.1 Air leakage control — weather barriers, air barriers and vapour barriers

Heated Crawl Space

See Keeping The Heat In - Chapter 6: Basement insulation: 6.3 Crawl Spaces

Heated Floor Area

The total useable area of your home that is heated, measured at the interior of the outer walls. This includes all above-grade heated areas, regardless of ceiling height, and below-grade heated areas, such as basements, that have a ceiling height of more than 1.2 meters (4 feet). The below-grade area is the sum of all areas on levels that are wholly or partly below grade.

Heating Degree Day (HDD)

The total number of Celsius degrees that the mean daily temperature of a location is below 18 °C, over the course of one calendar year. This unit of measure quantifies how cold Canada's many climate zones are relative to each other. It allows a fair relative comparison to be made, among homes in various climate zones, of the amount of space heating required over the course of one calendar year. The higher the average HDD value, the colder a location and the longer the heating season.

Heating Seasonal Performance Factor (HSPF)

The heating performance of a heat pump is indicated by the heating seasonal performance factor (HSPF) which is the amount of heat delivered, divided by the amount of electricity consumed by the heat pump over its period of use during the heating season. The higher the HSPF, the more efficient the heat pump.

Heating System

See Keeping The Heat In - Chapter 9: Operating your house: 9.1 Operating and Maintaining the Heating, Ventilating and Air-conditioning System

Heating, Refrigeration And Air Conditioning Institute Of Canada (HRAI)

See www.hrai.ca

High-Efficiency Motors

See Direct Current (DC) Motors

Home Ventilating Institute (HVI)

See www.hvi.org

Humidifier

A device that may be portable or incorporated into the heating system’s ductwork to increase the level of humidity in a house.

Humidistat

A control mechanism that regulates the operation of a humidifier, dehumidifier or ventilator based on the amount of humidity in the house air.

Humidity

See Relative humidity

Hygrometer

A device used to measure relative humidity.

The EnerGuide Housing Glossary – I

Indoor Air Quality (IAQ)

A general term relating to the monitoring and reduction of unhealthy chemical and biological contaminants in the air within a building.

Indoor wood-burning boiler system

A wood-fired hydronic heating system consists of a boiler that heats hot water. The hot water is then piped to convective heaters, such as cast-iron radiators, baseboard and cabinet heaters, a piping system that runs through the floor or ceiling, or fan-assisted coils.

Some of today's more advanced wood- or solid fuel-fired indoor boilers have efficiencies in the 80 percent range. These units use advanced wood-burning technologies whereby wood is gasified and smoke is re-burned, thus reducing smoke levels, burning the fuel at higher temperatures and increasing overall efficiency. These systems commonly use a thermostatically controlled blower fan to accurately supply combustion air, which reduces smouldering fires and creosote buildup in the chimney. This also results in substantially less wood being consumed compared to older or conventional indoor and outdoor wood boilers.

Inert Gas Fills

The inside of the window's glass, or insulated glazing (IG) unit can be filled with an odourlesss, colourless, harmless inert gas, such as argon or krypton, to reduce heat transfer through the glass. For maximum efficiency, argon is normally put into double-glazed units and krypton is put into triple- or quad-glazed units.

Insulation Values
  • Nominal RSI-value (R-value) of insulation (pre-construction) represents the resistance to the flow of heat of a given thickness of insulation. The higher the RSI-value (R-value), the better the insulation. RSI is the metric unit and is measured in m2°C/W while R is its imperial equivalent and is measured in ft2°F/W. RSI-1 = R-5.678.
  • Effective RSI-value (R-value) of assembly (post-construction) represents the resistance to the flow of heat of the entire wall, ceiling or floor assembly considering the structure, insulation, framing, sheathing and all finishing. Typically this value is lower than the nominal RSI-value (R-value) of the insulation because the framing material has a lower RSI-value (R-value) than the insulation.

For example, wall studs and top and bottom plates will reduce the effective insulation value of an insulated wall; while sheathing, drywall and the exterior finish can increase a wall’s thermal resistance. In practical terms, for example, RSI 3.52 (R-20) batt insulation in a 2 x 6 wall might yield an effective insulation value of only 2.99 (R-17).

Integrated Mechanical System

An integrated mechanical system (IMS) performs three functions: space heating, domestic hot water heating and continuous heat recovery ventilation. An IMS saves energy by using a sophisticated control system to ensure that excess heat generated by one function is used by the other functions, thereby maximizing energy recovery.

An IMS typically incorporates a boiler as the heat generator. The boiler delivers hot water to a coil inside an energy-efficient air handler to circulate conditioned air throughout the house. An interconnected heat recovery ventilator delivers continuous ventilation and an additional heat exchanger provides domestic hot water. Other options, such as air conditioning and zoned radiant floor or hydronic heating, may be included with some systems.

For a system to attain IMS certification, it must be tested to the CAN/CSA P.10-07 Standard by a third-party testing agency. The CAN/CSA P.10-07 Standard determines the efficiency of the system by calculating the overall thermal performance factor (OTPF) of the system while it is in space heating, water heating and ventilating modes.

In addition, the CAN/CSA P.10-07 Standard includes an energy performance target that establishes a level of energy efficiency that outperforms and uses less energy than the sum of its individual parts. Without the integrated control system, individual components with their own individual control systems are highly unlikely to meet the energy performance target.

Interior-Grade Caulking

See Keeping The Heat In - Chapter 3: Materials: 3.3.2 Sealants

The EnerGuide Housing Glossary – J

Joist

One of a series of horizontal or inclined wooden members, usually of 50mm (2 in.) nominal thickness, used for support in floors, ceilings or roofs.

Joist header space – see “Header space”

 

The EnerGuide Housing Glossary – K

Kilowatt-hour (kWh)

A unit of measurement of the consumption of electric energy over a fixed period of time specifically, the use of 1,000 watts for 1 hour. It can best be visualized as the amount of electricity consumed by ten 100-watt bulbs operating for one hour. One kilowatt-hour (kWh) equals 3.6 million joules or 3.6 megajoules (MJ).

The EnerGuide Housing Glossary – L

Latex Acrylic Caulking

See Keeping The Heat In - Chapter 3: Materials: 3.3.2 Sealants

Light Fixtures

See Keeping The Heat In - Chapter 4: Comprehensive air leakage control: Figure 4-2 Typical Leakage areas

Loose-Fill Insulation

Loose-fill insulation options include cellulose fibre, glass fibre and mineral fibre. Loose-fill insulation is suitable for walls and floors and excellent in attics and enclosed spaces, such as roofs, where the space between the joists may be irregular or cluttered with obstacles.

Read more about loose-fill insulation and other insulation types in Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Batt or blanket insulation

Low-E Coatings

Low-E, or low-Emissivity, glass has a fine coating of metal to reduce heat loss in the winter and heat gain in the summer, through the glass, by up to 30 percent. There are two types of low-E coatings: hard coat and soft coat. Both increase energy efficiency; however, some types of soft-coat low-E glass can dramatically reduce the amount of the sun's heat coming into the home.

The EnerGuide Housing Glossary – M

Masonry Heater

Masonry heaters are site-built or site-assembled solid-fuelled heating devices consisting of a firebox, a heat exchanger comprised of channels built from high-temperature firebrick and/or pre-cast masonry components and an exterior of brick, tile or stone. Heat from a short but very hot, efficient and smokeless fire is absorbed by the thermal mass that slowly radiates into the house for more than 12 hours at a time.

Medium-Or High-Density Foam

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Spray foam insulationn

Moisture Barrier

Often referred to as a ‘vapour diffusion retarder’ (VDR), it is a material used to retard the passage or flow of vapour or moisture into or through walls, roofs and foundations.

Read more about moisture in homes in Keeping The Heat In - Chapter 2: How your house works: 2.4.1 Sources of moisture in the home

Moisture Penetration

See Keeping The Heat In - Chapter 2: How your house works: 2.4 Control of Moisture Flow

Moisture Problems

See Keeping The Heat In - Chapter 2: How your house works: 2.4 Control of Moisture Flow

Mould

A fungus that grows on surfaces or in materials as a result of damp conditions; can have serious health implications for occupants if it occurs in a home.

If you suspect mould growth in your home, it must be thoroughly removed, the affected areas cleaned and disinfected, and contaminated materials properly disposed of. To control and reduce the potential for mould growth, control sources of moisture, maintain indoor humidity at recommended levels and remedy water infiltration and leakage.

Read more about moisture in homes in Keeping The Heat In - Chapter 2: How your house works: 2.4.1 Sources of moisture in the home.

For detailed information, look for resources at the Canada Mortgage and Housing Corporation website: www.cmhc.gc.ca

The EnerGuide Housing Glossary – N

Natural Gas

A mixture of gaseous combustible hydrocarbons made up mostly of methane but also smaller amounts of ethane, propane and butane. Natural gas is piped to buildings for space heating, domestic hot water, cooking, fireplaces and clothes drying.

Natural Infiltration

The movement of outdoor air into rooms and other spaces in a building through intentional openings, such as windows and doors, and through unintentional openings in the building envelope, such as cracks and gaps around service penetrations. Natural infiltration is driven by stack effect and wind.

Net-Metering

The use of a single electricity meter to measure household consumption as well as generation of electricity by wind or solar photovoltaic systems. The net electricity generated or consumed is purchased from or sold to the utility, respectively.

Nominal RSI

Nominal RSI-value (R-value) of insulation (pre-construction) represents the resistance to the flow of heat of a given thickness of insulation. The higher the RSI-value (R-value), the better the insulation. RSI is the metric unit and is measured in m2°C/W while R is its imperial equivalent and is measured in ft2°F/W.  RSI-1 = R-5.678.

The EnerGuide Housing Glossary – O

Oil-Fired Boiler System

An oil-fired boiler uses the same type of burner as an oil-fired, forced-air furnace, although a boiler is often smaller and heavier. There is no circulating fan and filter housing as there is in a forced-air system. Instead, most boilers require a circulating pump to push heat through the pipes and the radiator system. The seasonal efficiency of old conventional hydronic systems is similar to that of conventional forced-air systems, which is approximately 60 percent.

Oil-Fired Furnace System

An oil-fired furnace system consists of a burner fed by heating oil firing into a combustion chamber in the furnace. The oil storage tank is usually located in the house. The combustion gases pass through the furnace, where they release heat across a heat exchanger. The gases are then exhausted to the outside through a flue pipe and chimney.

For most systems, a barometric damper, acting as a valve in the flue pipe, isolates the burner from changes in pressure at the chimney exit by pulling varying quantities of heated room air into the exhaust. A circulating fan passes cool house air from the cold air return ducts over the furnace heat exchanger, where the air warms up and then passes into the hot air ducts, which distribute the heated air throughout the house.

Orientation

The siting of a building on a lot. The term is often used when discussing solar orientation, which is the siting of a building with respect to access to solar radiation.

Outdoor wood-burning boiler system

Most outdoor boilers look like a metal garden shed with a chimney. Heated water is pumped from the boiler to the house through an underground, insulated pipe. The water then passes through a heat exchanger and releases its heat to a forced-air stream (e.g., fan coil), or it is distributed to baseboards, wall registers or a piping system that runs through the floor or ceiling. With another heat exchanger, the boiler water can also heat domestic hot water. Cooled water is then sent back to the boiler for reheating through a second insulated underground pipe.

Outdoor boilers can burn various types of wood and wood by-products, as well as grains, coal and straw bales. Some units also include secondary heating systems, such as oil burners, for backup heating.

Overall Thermal Performance Factor (OTPF)

Determines the efficiency of an Integrated Mechanical System when it is in space heating, water heating and ventilating modes, or a combo system when it is in space heating and water heating modes. The higher the rating the better efficiency.

The EnerGuide Housing Glossary – P

Passive Solar Gain

The amount of heat gained by the house from solar radiation (sunlight) entering through glazing (windows, skylights and glazed components of doors). This does not include energy from dedicated panel panel-default solar heating systems that use solar collectors to convert sunlight into usable heat or electricity. The amount of solar gain will depend on several factors, such as the type and area of glazing, orientation, thermal mass, latitude and amount of shading (e.g. overhangs, trees, etc.). Generally, in the Northern Hemisphere, south facing windows provide the most solar gain.

Penetration

See Keeping The Heat In - Chapter 4: Comprehensive air leakage control: Figure 4-2 Typical Leakage areas

Plumbing Stack

see Keeping The Heat In - Chapter 5: Roofs and attics Figure 5-6 Sealing the plumbing stack

Polyethylene

A common plastic used to make air and vapour barriers. Referred to by construction professionals in shortened form as "poly".

Read more about loose-fill insulation and other insulation types in Keeping The Heat In - Chapter 3: Materials: 3.3.1 Choosing an air barrier material - Sheet material Polyethylene sheeting

Polyisocyanurate / Polyisocyanurate Foam Boards

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Rigid board insulation and Polyurethane and polyisocyanurate boards

Polyurethane

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Rigid board insulation and Polyurethane and polyisocyanurate boards

Pellet-burning appliances [Pellet-burning space heater / Pellet-burning furnace / Pellet-burning boiler]

Clean-burning and energy-efficient pellet appliances burn pellets made from ground wood or corn, grain or cherry pits. If properly adjusted, pellet-burning appliances can operate at lower emission levels than wood-fired appliances. Pellet appliances typically include a hopper that holds 20-60 kg of fuel and a screw auger that automatically moves the fuel from the hopper into the combustion chamber. Some appliances feature bulk feeding from an external storage supply. The fuel burns cleanly because it is fed to the chamber at a controlled rate and matched with the right amount of combustion air. Many pellet appliances include directly connected combustion air and direct venting. The ash and clinker residue are easy to remove.

Piping Insulation / Insulate Piping

Insulating the hot and cold water pipes within 2 to 3 m of the water heater is the most cost effective improvement that can be made to existing or new installations. Several products can do this job, but the easiest one to use is the pop-on insulating foam sleeves. They are very effective and can be mitred at bends in the pipe. The safety guidelines for insulating gas-fired, propane and oil-fired water heaters differ from those for electric water heaters. Follow the manufacturer’s instructions or keep the pipe insulation at least 15 cm (6 in.) away from the exhaust vent at the top of natural gas/propane and oil water heaters. There are no restrictions for electric water heaters. Insulating the cold water pipes will minimize condensation on the pipes. This prevents dripping on ceiling tiles and basement floors.

The EnerGuide Housing Glossary – R

Recessed Lighting Fixtures

Keeping The Heat In - Chapter 5: Roofs and attics - Figure 5-5 Keep insulation away from a recessed light fixture by creating a barrier

Reflective Foil Membrane

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Reflective bubble foil insulations and radiant barriers

Relative Humidity

The amount of water vapour in the air (expressed as a percentage) compared to the amount of water that air at the same temperature could hold if the air were totally saturated.

Read more about humidity in Keeping The Heat In - Chapter 2: How your house works: 2.4.2 How much humidity?

Renewable Energy

Renewable energy is energy obtained from natural resources that can be naturally replenished or renewed within a human lifespan, that is, the resource is a sustainable source of energy. Some natural resources, such as moving water, wind and sunshine, are not at risk of depletion from their use for energy production. Biomass, however, is a renewable resource only if its rate of consumption does not exceed its rate of regeneration. A wide range of energy-producing technologies and equipment have been developed over time to take advantage of these natural resources. As a result, usable energy can be produced in the form of electricity, industrial heat, thermal energy for space and water conditioning, and transportation fuels.

Renewable Energy Source

A source of energy from an inexhaustible source such as wind and solar or from naturally and rapidly renewing sources such as wood and crop biomass waste.

Rigid-Board Insulation

Rigid board insulation (insulating boards) is currently manufactured from mineral fibre or foam plastic materials. These materials have a high insulating value per unit thickness although the cost per RSI value is greater than that for loose-fill or batt or blanket insulations.

Insulating boards are lightweight and easy to cut and handle. Fitting them into irregular spaces, however, can be a tedious process. Some boards are available with special coverings (e.g. a fire-resistant material) and their own system of attachment. Some board materials can be ordered pre-cut to specific sizes for an additional cost.

Rigid board insulation options include expanded polystyrene, extruded polystyrene, mineral fibre rigid board and polyurethane and polyisocyanurate plastic boards.

Read more about rigid-board insulation in Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types - Rigid board insulation.

Rim joist – see “Header”

Rim joist space – see “Header space”

Roof Space

The space between the upper floor ceiling and roof or between a knee wall and a sloping roof. Also called "attic".

R-2000

R-2000 is a voluntary standard administered by Natural Resources Canada (NRCan) and is delivered through a network of service organizations and professionals across Canada.

Developed in partnership with Canada's residential construction industry, R-2000 is one of the initiatives offered by NRCan's Office of Energy Efficiency. This initiative’s aim is to promote the use of cost-effective energy-efficient building practices and technologies. Through the use of third-party evaluators and a government of Canada supported certification process homeowners are assured of real value and consistency.

Houses built to the R-2000 Standard typically exceed the energy performance requirements of the current Canadian building codes and are recognized by meeting a high standard of environmental responsibility.

Since its introduction over 30 years ago, the R-2000 Standard has become the benchmark for energy efficient new home building in Canada. The Standard is continually upgraded to include new technologies as it becomes established in the marketplace furthermore it is flexible enough to apply to any type of home.

The EnerGuide Housing Glossary – S

Sealant

See Keeping The Heat In - Chapter 3: Materials: 3.3.2 Sealants

Sealed Combustion

In a sealed combustion system, outside air is piped directly to the combustion chamber, and the furnace does not draw any air from inside the house for either combustion or vent gas dilution. This is desirable because it eliminates any potential for depressurization and drawing corrosive vapours inside a house, such as bleaches from a laundry zone, into the furnace combustion chamber. The majority of condensing furnaces are certified for installation that uses a “two-pipe,” sealed combustion configuration. However, some condensing furnaces can be installed by using a “one-pipe” configuration that draws combustion air from inside the home.

The main advantage of two-pipe, sealed combustion is that it isolates the combustion air system from the house. Consequently, the furnace is not affected by the operation of other appliances or exhaust fans in the home and does not cause depressurization of other appliances. The tight construction of an energy-efficient house combined with the operation of exhaust fans (such as kitchen and bathroom fans and clothes dryers) can cause spillage of flue gas and backdrafting from fuel-burning appliances. Sealed combustion units prevent this potential safety problem. Also, heating costs may be reduced slightly by decreasing the amount of heated air that is drawn from inside the house.

Most high-efficiency furnaces are designed and certified as two-pipe, sealed combustion systems, so they are well-suited to the tight construction of modern energy-efficient houses.

Seasonal Energy Efficiency Ratio (SEER)

Seasonal Energy Efficiency Ratio (SEER) is a measure of the energy efficiency of an air-conditioner and heat pump. The higher the SEER, the more efficient the equipment is.

Service Organization

A service organization is any organization or person who is registered with Natural Resources Canada and whose role is to implement and deliver the EnerGuide Rating System, ENERGY STAR® for New Homes and/or R-2000 Standard.

Set-Back Thermostat / Programmable thermostat

Except for some hydronic systems with slow response times, you can save energy by turning down your thermostat, and the best way to do this is to install a programmable setback thermostat. A basic programmable thermostat will provide a clock timer and allow at least two setback and reset periods a day.

For example, a temperature reduction could be programmed to start before bedtime and end before you get up in the morning. The second setback can reduce the temperature when everyone is away during the day and end just before you arrive in the evening.

A drop of 1°C (2°F) over an eight-hour period can save about 2 percent on your heating energy consumption. If you are away from home for more than three or four hours, it is worthwhile to turn down the temperature. In general, it is best not to reduce the temperature lower than 17°C (63°F), as there is a risk of moisture build-up in the exterior walls. If you want to reduce your temperature further, such as when you are away for extended periods of time (a week or longer), you must keep humidity levels low.

Read more about controlling moisture in Keeping The Heat In – Chapter 2 “How Your House Works”  2.4 Control of Moisture Flow.

Sheathing

Lumber, wood panels or other types of panels used to cover the exterior framework of a building.

Sill

The horizontal member forming the bottom of an opening for a door or window.

Sill plate

A wooden structural member anchored to the top of a foundation wall, upon which the floor joists rest.

Soffit

The underside of a roof where it overhangs the exterior walls. Soffit vents are installed horizontally along the underside of the trusses where they overhang the exterior walls. These vents help ensure air movement through the attic under the roof, while keeping rodents and birds out.

See Keeping The Heat In - Chapter 5: Roofs and attics for more information.

Solar Array

Photovoltaic modules are connected together into panels and arrays to meet various energy needs. The solar array is connected to an inverter that converts the Direct Current (DC) generated by the PV array into Alternating Current (AC) compatible with the electricity supplied from the grid. AC output from the inverter is connected to the home’s electrical panel or utility meter, depending on the configuration.

Solar Domestic Hot Water System

You can use the sun’s energy to heat water. In Canada, solar domestic hot water (SDHW) systems are usually selected and sized to provide approximately 60 percent of the hot water requirements for an average home, depending on the local climate and hot water use.

Solar water heater systems include collectors, a circulating pump, a storage tank or tanks, and controls. They are commonly configured to preheat water with a conventional water heater for backup. Solar preheat units typically have two tanks. One tank stores solar heat and one is connected to a conventional storage water heater that can be heated by any source (electric, gas or oil).

A tankless (on-demand) water heater can also be used instead of the second tank.

Solar photovoltaic (PV) system

A system that directly converts sunlight into electricity. When light energy strikes the surface of a photovoltaic device, a direct current is created.

Solar Thermal

Solar thermal technologies (also known as panel panel-default solar systems) involve the conversion of solar radiation into heat and include the use of pumps or fans to panel panel-defaultly transfer the heat to storage or for distribution directly to its intended use. The key component of any panel panel-default solar system is the solar collector, which absorbs the sun’s radiant energy and transforms it into usable heat.

Various types of collectors are used in solar energy conversion, depending on the application and temperature requirements:

  • Unglazed metal and plastic flat plate collectors are used for low temperature applications such as residential pool heating and ventilation air heating for commercial and industrial buildings
  • Glazed flat plate and vacuum tube collectors are used for mid-range temperature applications such as domestic hot water and space heating and cooling applications
  • Concentrating collectors that focus the sunlight onto a much smaller area are used for higher temperature applications such as industrial process heat, absorption cooling, and large-scale solar thermal power applications to generate steam for electricity generation
Solid Fuel-Fired Furnace System

Solid fuel-fired furnaces can be stand-alone units with their own blower fans and controls or they can be installed beside an existing furnace as an add-on furnace. Various models will burn wood, coal, wood pellets, corn, cherry pits and some grains. It is very difficult to obtain manufacturers' combustion efficiency ratings for the burning of solid fuels, and even if some are advertised, they should be treated with caution. If you are purchasing a new solid fuel-fired furnace, look for equipment certified to Canadian Standards Association (CSA-B415.1) or the Environmental Protection Agency (EPA 40 CFR Part 60). These standards are based on maximum levels of particulate emissions per hour from a wood-burning appliance and they do not provide a combustion efficiency rating. However, the reduction in particulate emissions is closely related to more efficient combustion.

Solid fuel-fired furnaces can be stand-alone units with their own blower fans and controls or they can be installed beside an existing furnace as an add-on furnace. Various models will burn wood, coal, wood pellets, corn, cherry pits and some grains.

It is very difficult to obtain manufacturers' combustion efficiency ratings for the burning of solid fuels, and even if some are advertised, they should be treated with caution.

If you are purchasing a new solid fuel-fired furnace, look for equipment certified to Canadian Standards Association (CSA-B415.1) or the Environmental Protection Agency (EPA 40 CFR Part 60). These standards are based on maximum levels of particulate emissions per hour from a wood-burning appliance and they do not provide a combustion efficiency rating. However, the reduction in particulate emissions is closely related to more efficient combustion.

Space Cooling / Air Conditioning / Cooling / Cooling system

The cooling of the rooms or spaces within a building. Air conditioning is a good example of where oversizing is clearly detrimental to comfort, cost of operation and equipment performance. An oversized system will lower house temperature too quickly without removing excess humidity. The result is a house that is cool and damp, which in turn can promote mould growth and musty odours. Higher indoor temperatures (e.g. 26°C/79°F) with reduced humidity levels are more comfortable and allow for more energy savings.

Air conditioners should be serviced and maintained regularly. They become inefficient when the inside coil is dirty, when the airways on the outdoor condenser unit are blocked and when the refrigerant level runs low. You can do some simple maintenance yourself. For example, clean or change the air filter, keep the outside condenser free from obstructions such as plants and leaves. In addition, a service contractor should periodically maintain your unit. Check your owner’s manual for information on maintenance.

Space Heating

The heating of the rooms or spaces within a building.

Spray Foam Insulation/Spray Foam/Spray-On/Closed- or Open-Cell Polyurethane Foam

Spray-foam insulation is made of plastic resin (e.g. soy-based resins or resins made from recycled plastic) and a catalyst, which is prepared and applied on the job site. Spray kits for this type of insulation are available to the consumer, but employing a certified installer who is trained in the application of the specific product will ensure the best results.

The liquid foam is sprayed directly onto the building surface or poured into enclosed cavities with a pump-driven applicator. The foam expands in place and sets in seconds.

There are two types of foam: low density and high density. When installed on interior surfaces, all plastic-based foam insulation must be covered with a fire-resistant material – typically 13-mm (1/2-in.) drywall – that is mechanically fastened to the building. All foam plastics must be protected from prolonged exposure to sunlight. Options for spray-foam insulation include closed-cell polyurethane foam and open-cell polyurethane foam.

Stack effect

The vertical movement of air due to differences in indoor-outdoor air density that increases the buoyancy of the indoor air relative to that of the outdoor air. This difference occurs as a result of differences in indoor-outdoor temperature. The buoyancy forces driving stack effect increase with building height and temperature difference. In cold climates, stack effect tends to cause air to leak into the bottom of a building and out of the top.

Standby losses

The energy performance of electric water heaters is rated in standby loss measured in watts. This indirect measure of efficiency indicates the loss of heat from the tank. Better insulation around the tank reduces heat loss. A lower standby loss indicates higher efficiency.

Strapping

A wood batten fixed to the faces of walls and ceilings to support insulation, siding, drywall, lath and plaster and other finishes.

Read more about strapping and insulation in Keeping The Heat In "Insulating Walls": 7.2 Renovating The Interior

Stud

One of a series of regularly spaced wood structural members (usually 50 mm (2 in.) nominal thickness) used for walls and partitions.

Supplemental Heating System

Heating provided to an area in excess of the minimum required heating for that area, usually under separate thermostatic control and designed to offset occupant discomfort or to act as a backup to the primary heating system.

The EnerGuide Housing Glossary – T

Tank-type water heater / Storage tank water heater

Storage tank water heaters are the most common type installed in Canadian homes. As the name implies, these systems store heated water in a tank so a quantity of hot water is stored and available. When a tap is turned on, hot water flows from the storage tank. Unheated water flows into the tank to replace that hot water. A thermostat turns on the burner or electric element to maintain the water temperature in the tank.

To protect the inside of the tank from corrosion, storage tank water heaters are usually equipped with a galvanic anode. The anode is a metal rod of magnesium or aluminium alloys that is inserted into the tank from the top. The rate at which the anode dissolves depends on the mineral content or hardness of the water as well as the integrity of the enamel or epoxy coating inside the tank.

New water heaters must have a temperature and pressure relief valve. This safety device allows water that is too hot or under too much pressure due to a faulty temperature control to escape from the tank. Storage tank water heaters can be made more energy efficient by reducing standby loss. For gas- and oil-fired storage tank water heaters, efficiency can also be improved at the design stage by increasing the amount of heat transferred from the combustion gases to the water and by minimizing the amount of heat going out the vent or chimney.

Manufacturers incorporate design and construction features to improve the energy efficiency of storage tank water heaters. More efficient tanks have:

  • more tank insulation 
  • more efficient heat exchangers (for gas and oil tanks) so more heat is transferred from the energy source to the water
  • factory-installed heat traps, which minimize unwanted convection of heat out of the tank and within the pipes, but still allow water flow. Heat traps reduce standby losses from the piping and the tank.
Tankless water heater / instantaneous water heater

This type of water heater consists of either an electric element or a gas burner that heats flowing water and does not have a storage tank. It is also called on-demand, point-of-use, instantaneous or tankless water heater because it heats water only when it is needed, thereby eliminating continuous standby losses. A tankless water heater is usually more energy-efficient than a storage tank water heater.

Several on-demand gas-fired water heaters have enough delivery capacity to supply hot water for most houses. Their rated hot water flow rates are based on standard inlet and outlet water temperatures. In winter, intake cold water may be as cold as 5°C so take care when you select an on-demand water heater to account for the colder water temperature.

Gas-fired on-demand water heaters have either a continuous pilot light ignition system or an electronic ignition. Water heaters that have a continuous pilot light use energy even when no hot water is required.

Gas-fired on-demand water heaters are usually mounted on an outside wall so that the flue gases can be vented to the outside through a side wall vent.

Thermal Bridge / thermal bridging

A component, assembly or area of the building envelope that has noticeably higher thermal conductivity than the surrounding area of a house's structure, allowing heat to transfer more easily in and out across the envelope. Examples include framing members in insulated frame walls, metal window frames, balcony slabs, shear walls and steel studs. Depending on the size and number of the thermal bridges and their thermal characteristics, a significant reduction in the overall thermal insulation value of the envelope can result. Thermal bridges can cause higher heat loss (heat gain in summer), increased space heating and cooling energy consumption, comfort problems and condensation-related indoor moisture problems.

Thermal Efficiency

The efficiency of fuel-fired DHW equipment is expressed as thermal efficiency or the energy factor (EF). The higher the number, the more efficient the water heater.

Thermal Resistance

To rate insulation, its resistance to heat flow is measured, and products are labelled with both an RSI value (Résistance Système International) and an R-value. The R-value is the imperial measurement, and the RSI-value is the metric measurement of thermal resistance.

Use the following equation to convert an R-value (imperial) to RSI (metric).The higher the resistance value, the slower the rate of heat transfer through the insulating material. One brand of insulation may be thicker or thinner than another, but if they both have the same RSI value, they will control heat flow equally well.

Conversion of an R-value to RSI
R-value ÷ 5.678 = RSI
Example: 20 ÷ 5.678 = RSI 3.52

Tilt Angle

The angle between the plane of the surface of a solar collector, or the roof directly supporting it, and the horizontal plane

Trim

See Keeping The Heat In - Chapter 4: Comprehensive air leakage control - 4.2.5 Tips on sealing some of the leakiest areas - Trim areas

Truss

A rigid, open web, metal or wood framework used to support floors or roofs. Trusses can also be used in the walls of energy efficient houses as a way to provide increased wall thickness for insulation.

The EnerGuide Housing Glossary – U

U-Factor

A measure of the heat transferred (or lost) through windows and doors. The lower the U-factor, the better the energy efficiency of a window. The inverse of U-factor (1/U-factor) identifies the heat resistance, expressed in RSI. The higher the RSI, the better the window is at resisting heat loss. You can use these values to choose windows to capture the heat from the sun or to reduce heat loss.

Urethane Foam

See Keeping The Heat In - Chapter 3: Materials: 3.1.5 Summary of insulation types

The EnerGuide Housing Glossary – V

Vapour Barrier

The vapour barrier resists the diffusion of water vapour from the inside to the outside of the building envelope. It protects the insulation and structure from moisture damage that can be caused if water vapour moves into and condenses in the envelope assembly. In some applications, the vapour barrier also acts as the air barrier by reducing heat loss as it prevents air from passing in and out through the envelope (i.e. an air and vapour barrier).

Read more about air and vapour barriers in Keeping The Heat In - Chapter 2: How your house works: 2.3.1 Air leakage control — weather barriers, air barriers and vapour barriers

Ventilation

The overall process of the controlled exchange of indoor air with outdoor air, including the treatment (filtering, tempering) of outdoor air, the distribution of outdoor air to the habitable rooms of the house, and the circulation of air within the rooms. It also includes the venting of exhaust air from bathrooms, kitchens and other spaces.

Read more about ventilation in Keeping The Heat In - Chapter 9: Operating your house: 9.4.4 Increasing ventilation

Ventilation System / Ventilating

Ventilation systems work under two main categories: balanced and unbalanced. Unbalanced is most common where exhaust fans are used and replacement air comes from air leakage. This can result in reduced house pressures and limited success in ventilating the house properly. Balanced ventilation incorporates a system where exhausted air is replaced with a dedicated source of incoming air. This helps keep house pressures close to neutral and helps to ventilate the house more evenly.

Read more about ventilation systems in Keeping The Heat In - Chapter 9: Operating your house: 9.4.4 Increasing ventilation

The EnerGuide Housing Glossary – W

Wall Trims

See Keeping The Heat In - Chapter 4: Comprehensive air leakage control: 4.2.5 Tips on sealing some of the leakiest areas - Trim areas

Walls Above Grade

See Above Grade Area

Weatherstripping

Flexible strips of felt, rubber, metal or other material, affixed along the edges of doors and the operable parts of windows to block air leakage and reduce heat exchange with the outdoors. Weatherstripping comes in a variety of shapes: flat strip, tube or V (i.e. V-strips), and can be designed to work under compression or by sliding along the joint. To be effective, the product must close the gap and not allow air to pass. Some products get hard – and less effective – in cold weather when you need them the most.

Read more about weatherstripping in Keeping The Heat In - Chapter 3: Materials: Figure 3-5 Types of weatherstripping

Wind power generation system

The kinetic energy in wind can be converted into useful forms of energy such as mechanical energy or electricity. Today, wind is used increasingly to generate electricity. Wind energy is captured only when the wind speed is sufficient to move the turbine blades, but not in high winds when the turbine might be damaged if operated.

Wood-burning furnace system

Solid fuel-fired furnace system

Wood-burning stove

A wood-burning space-heating device.

New wood-burning technologies feature firebox insulation that keeps temperatures high, preheated combustion air, and internal baffles that ensure the complete burning of gases before they leave the appliance, reducing the amount of pollutants released into the atmosphere.

Wood Energy Technology Transfer Inc (Wett Inc)

www.wettinc.ca