Glossary
The basics.
Retrofitting: The process of making improvements or upgrades to existing buildings to enhance energy efficiency, comfort, or safety.
Ventilation: The process of exchanging indoor air with outdoor air to maintain indoor air quality and remove pollutants, odours, and moisture.
Natural Ventilation: Ventilation achieved through the use of openings such as windows, vents, and trickle vents to allow fresh air to enter and stale air to exit the building naturally. It relies on natural forces such as wind and buoyancy to drive air movement.
Purge Ventilation: A type of natural ventilation that involves opening windows or vents to allow rapid air exchange, typically used to flush out pollutants or odours from a space.
Trickle Vents: Small adjustable vents installed in window frames or walls to provide continuous background ventilation while minimizing heat loss.
Whole-House Ventilation System: A ventilation system designed to provide ventilation to all rooms within a building, ensuring consistent airflow and air quality throughout.
Passive Ventilation: A ventilation strategy that utilizes natural airflow principles and passive ventilation openings, such as vents or chimneys, to facilitate air exchange without the need for mechanical fans or systems.
Humidity Control: Measures taken to regulate indoor humidity levels to prevent excessive moisture build-up, which can contribute to condensation, mould growth, and indoor air quality issues.
Regulatory Compliance: Ensuring that retrofitting works and ventilation installations comply with relevant building regulations, standards, and guidelines to ensure safety, performance, and durability.
A
Absolute Humidity: This is the actual amount of water vapour present in a unit volume of air, typically measured in grams per cubic meter (g/m³).
Aerogel: a solid material of extremely low density, produced by removing the liquid component from a conventional gel.
Alternating current (AC): It is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current flowing in power lines and normal household electricity that comes from a wall outlet is alternating current.
ACH air changes per hour: Air changes per hour (ACH) is a measurement of how often the air in a space is replaced with fresh or recirculated air. It’s also known as “air change rate” or “air exchange rate.
Adventitious air: Natural ventilation that comes into a room from outside through cracks in doors, windows, and floorboards.
Air Leakage: The unintentional flow of air into or out of a building through gaps, cracks, or openings in the building envelope. Minimizing air leakage helps to improve energy efficiency and indoor air quality.
Auto bypass: The automatic by-pass valve is designed to maintain a minimum flow rate in heating systems fitted with thermostatic radiator valves. When all the TRVs are open the by-pass valve remains closed, allowing the full boiler output to circulate around the heating system
B
Balancing: Balancing a heating system involves adjusting the flow of hot water to each radiator so that they heat up at the same rate. This improves energy efficiency and comfort,
Benzene: It is a natural component of crude oil and is produced during various industrial processes, including petroleum refining and the combustion of fossil fuels. It is widely used as a starting material in the manufacturing of many important chemicals, such as plastics, synthetic fibres, detergents, pesticides, and pharmaceuticals.
Building Regulations: Building regulations in the UK are a set of national standards and requirements that govern the construction and alteration of buildings to ensure safety, accessibility, energy efficiency, and sustainability. These regulations apply to most types of buildings, including residential, commercial, and industrial structures. They are enforced by local authorities or approved inspectors and are designed to protect the health and safety of occupants as well as the environment. All documents here.
C
Capillary Action: Moisture can be drawn into the building through capillary action in materials like concrete, brick, or wood.
Carbon/energy reduction: Are related concepts focused on lowering the environmental impact of energy consumption, particularly with regard to reducing carbon emissions and minimizing energy use. Both are key components of efforts to combat climate change, reduce global warming, and promote sustainability.
Closed cell: Closed cell insulation is made from a foam material where the individual cells within the foam are completely sealed, preventing air movement and maximizing its insulating properties by trapping air within each cell
Coefficient: A number used to multiply a variable. Example: 6Y means 6 times Y, and “Y” is a variable, so 6 is a coefficient.
Condensation: Condensation occurs when warm, moist air comes into contact with cooler surfaces, causing the water vapour to condense into liquid water. This often happens on windows, walls, and other cold surfaces.
Construction Defects: Poor construction practices, such as improper sealing or insulation, can allow water to infiltrate the building envelope.
Competent person: A competent person is someone who has sufficient training and experience or knowledge and other qualities that allow them to assist you properly. The level of competence required will depend on the complexity of the situation and the particular help you need.C
D
Dew Point: The temperature at which air becomes saturated with moisture and condensation occurs.
Dehumidification:The process of removing excess moisture from the air to reduce humidity levels indoors.
Direct current (DC). Is electricity flowing in only one direction, like water constantly flowing through a hose, whereas the opposite, “alternating current” (AC), would be like water flowing back and forth in the hose; essentially, a battery is a good example of a DC power source, where the current always flows from the positive to the negative terminal.
DNO: (district network operator) A Distribution Network Operator (DNO) is a company that owns and operates the infrastructure that delivers electricity to homes and businesses in a specific area of Great Britain. DNO’s are licensed by the Office of Gas and Electricity Markets (Ofgem).
Ductwork: A system of ducts or pipes used to distribute ventilation air throughout a building, connecting ventilation outlets to supply and extract points.
E
ECO (Energy Company Obligation): Funded scheme that is a government initiative in the United Kingdom designed to address fuel poverty, reduce carbon emissions, and improve energy efficiency in households. It requires larger energy suppliers to deliver energy efficiency measures to domestic properties.
Efflorescence: The white, powdery deposit left on the surface of masonry materials when water evaporates and leaves behind dissolved salts.
EPR: An Energy Performance Report (EPR) is a document that provides an assessment of how energy is used in a building or facility, with a focus on its overall energy efficiency and sustainability. It typically includes an analysis of energy consumption, identifies inefficiencies, and recommends measures for improving energy performance. These reports are often part of efforts to comply with energy regulations, reduce operational costs, and minimize environmental impacts.
EPC: An Energy Performance Certificate (EPC) is a document that provides an assessment of the energy efficiency of a building. It gives the building a rating based on its energy consumption and how well it uses energy, helping potential buyers or tenants understand the energy performance of a property. The EPC is typically required during property transactions or rentals and is commonly used in many countries, particularly within the European Union, the UK, and other regions with energy efficiency regulations.
Energy Efficiency Measures: Improvements or upgrades aimed at reducing energy consumption and improving the energy performance of a building, such as insulation, double glazing, heating controls, and ventilation systems.
Ethylene glycol: One of the main uses of ethylene glycol is as a coolant in automotive engines.
It is also used in the manufacture of polyester fibres, plastics, and polyethylene terephthalate (PET) resins, which are commonly used in beverage bottles and food containers.
Exhaust Fans: Mechanical devices used to remove stale air from specific areas such as bathrooms, kitchens, or utility rooms. They help to reduce moisture levels and prevent the build-up of odours and pollutants.
F
Finlock Guttering: Finlock gutters are a system of guttering made of concrete. They’re usually found in properties that were built between the 1950s and the 70s. The Purpose for Which Finlock Gutters Were Introduced. These gutters were formally introduced as a replacement to cast iron guttering systems.
Flooding: Flooding from heavy rain, overflowing rivers, or burst pipes can introduce large amounts of water into a building.
Formaldehyde: It is a colorless, strong-smelling gas commonly used in various industrial applications, as well as in household products. It is a simple organic compound with the chemical formula CH2O. Formaldehyde is highly reactive and versatile, making it useful in the production of many materials, including plastics, textiles, paints, adhesives, and building materials like plywood and particleboard.
G
Groundwater: Water can seep into basements or crawl spaces from the surrounding soil, especially in areas with high water tables or poor drainage.
Glaser Method: The Glaser method is a way to calculate the amount of interstitial condensation that occurs during winter and the amount of evaporable water in the summer. It also identifies vapour diffusion, which is how easily water vapour can pass through a building’s fabric. However, the Glaser method has some limitations, including that It assumes that vapour only moves in one direction, from inside to outside.
H
Heat loss area: The perimeter around a property that has no heated space (a heated garage would not be classed as heat loss but unheated would, a neighbour’s party wall would not be classed as heat loss unless proven to be).
HAMM Principles: For any building to be an energy efficient, healthy, moisture free building envelope there is a clear need to manage the balance of Heat, Air, Moisture movement (HAMM) throughout the process of the building’s life cycle from design, construction, completion, and use.
Humidity: Humidity refers to the amount of water vapour present in the air. It is a measure of the moisture content in the atmosphere. Humidity plays a significant role in determining how comfortable we feel in a given environment, as well as influencing various natural processes and phenomena.
Hygroscopic Materials: Hygroscopic materials are substances that have a natural affinity for moisture in the air, causing them to absorb water vapour from their surroundings. These materials can attract and retain moisture molecules, often leading to changes in their physical properties or chemical composition. Some common examples of hygroscopic materials include:
- Silica Gel: Often found in small packets within product packaging, silica gel is a highly porous and hygroscopic material used to absorb moisture and maintain dryness.
- Wood: Wood is inherently hygroscopic, meaning it can absorb and release moisture from the surrounding environment. Changes in moisture content can cause wood to swell, shrink, or warp.
- Salt: Many types of salt, such as table salt (sodium chloride), are hygroscopic and readily absorb moisture from the air. This property is why salt is typically used as a desiccant to absorb moisture and prevent clumping.
- Certain Metals: Some metals, such as iron and magnesium, can exhibit hygroscopic properties under specific conditions, particularly when they form hydrated salts or oxides.
- Sugar: Sugar is hygroscopic and tends to clump together in humid environments due to its ability to absorb moisture from the air. Hygroscopic materials are commonly used in various applications, including food preservation, pharmaceuticals, electronics manufacturing, and construction.
They are utilized to control humidity levels, prevent moisture-related damage, and maintain the quality and integrity of products or materials.
Heat Recovery Ventilation (HRV): A ventilation system that recovers heat from outgoing stale air and transfers it to incoming fresh air, improving energy efficiency while providing ventilation
I
Interstitial condensation: Occurs when warm, moist air penetrates a building’s insulation layer and condenses on colder surfaces within the structure, such as walls, floors, or roofs. This can happen when the interior of the building is warmer than the exterior, which is often the case during colder months. As the air cools, it reaches its dew point, causing moisture to condense within the wall cavity.
Indoor air quality (IAQ): Indoor air quality (IAQ) is the quality of the air in a building, and how it affects the health and comfort of people who are in it. IAQ can be influenced by many factors, including: Temperature and humidity, Ventilation, Mold, and Exposure to chemicals.
Inverter. An electronic device that converts direct current (DC) to alternating current (AC). This allows you to use AC devices, like TVs, computers, and lights, with DC power sources, like batteries.
L
Load compensation. A control feature that adjusts the output of a boiler or heating system based on the difference between the actual room temperature and the target temperature. Instead of simply turning the heating on or off, load compensation allows the system to modulate its heat output, making it more efficient and reducing energy waste.
M
Mildew: Mildew is a type of fungus that appears as a white, thread-like growth on organic matter or living plants. It’s often associated with damp places like shower walls, windowsills, and basements, and can produce a musty odour.
Mold: Fungi that grow in damp or humid conditions. Mold growth in buildings can be harmful to both the structure and occupants’ health.
Moisture Meter: A device used to measure the moisture content of building materials, such as wood, drywall, or concrete.
O
Occupant Activities: Activities such as watering indoor plants excessively or not properly ventilating bathrooms and kitchens can contribute to moisture build-up.
Open cell: Open cell insulation is a type of foam insulation with interconnected, open cells that allow air to flow through, creating a softer, more flexible material often used for soundproofing and filling irregular spaces.
Optimization. The process of making a heating system more efficient by reducing energy waste, improving comfort, and lowering heating costs. It involves using smart controls, sensors, and automation to ensure that heat is only used when and where it is needed.
P
Pas 2035: A publicly available specification developed by the British Standards Institution (BSI) in collaboration with various industry stakeholders. It provides a framework for the retrofitting of domestic buildings to improve energy efficiency, comfort, and environmental performance.
Pas 2030: Is a Publicly Available Specification (PAS) in the UK that sets out the requirements for the installation of energy efficiency measures in existing buildings. It is particularly relevant for organizations and contractors involved in retrofitting buildings with energy-saving technologies and improvements. PAS 2030 provides a framework for ensuring that energy efficiency measures are installed to a high standard, helping to reduce energy consumption and carbon emissions, in line with the UK’s sustainability goals.
Parallel: (solar panels). Solar panels are wired in parallel when the positive terminals of all the panels are connected together, and the negative terminals are connected together. This increases the amperage of the system while keeping the voltage the same.
Purge ventilation: is manually controlled ventilation of rooms or spaces at a relatively high rate to rapidly dilute pollutants and/or water vapour and may be provided by natural means (for example, an openable window) or by mechanical means (for example, a fan)
Pattress: A pattress or pattress box or fitting box is the container for the space behind electrical fittings such as power outlet sockets, light switches, or fixed light fixtures. Pattresse’s may be designed for either surface mounting or for embedding in the wall or skirting board.
Phase: In the UK electrical context, “phase” refers to the distribution of electrical load within a circuit, with “single phase” meaning there’s only one live wire supplying power to a household. Most UK homes are single phase.
Photovoltaic cells: Also known as solar cells, are devices that convert light energy into electricity. They are made of semiconductor materials, and are a key component of solar panel
Pulse test: A pulse test is a method for measuring a building’s air tightness by sending a pressure shockwave into the building and analysing the pressure decay. The test is a UK government-approved alternative to the more disruptive blower door method.
R
Relative Humidity (RH): The ratio of the actual amount of water vapour in the air to the maximum amount of water vapour the air can hold at a specific temperature, expressed as a percentage. Relative Humidity (RH): Relative humidity is a ratio of the amount of water vapour present in the air to the maximum amount of water vapour the air can hold at a given temperature, expressed as a percentage. For example, if the relative humidity is 50%, it means the air contains half the maximum amount of water vapour it could hold at that temperature.
Reciprocal: In mathematics, the reciprocal of a number is 1 divided by that number. Essentially, it is the inverse of a given number.
- For example:
- The reciprocal of 2 is 1/2.
- The reciprocal of 1/4 is 4.
- The reciprocal of 5 is 1/5.
S
Solar gain: Is the increase in temperature in a home caused by the sun’s heat. It occurs when short-wave infrared rays from the sun pass through windows and other transparent parts of a building, and are absorbed by objects and surfaces inside. The objects then emit heat in the form of long-wave infrared radiation, which can’t escape, making the area warmer.
Semiconductors. A substance that conducts electricity is called a conductor, and a substance that does not conduct electricity is called an insulator. Semiconductors are substances with properties somewhere between them.
Smart export guarantee: The SEG, launched on January 1, 2020, replaces the Feed-in Tariff (FiT) scheme. It ensures that those generating their own electricity from renewable sources (solar, wind, micro-CHP, etc.) are paid for the excess energy they send back to the grid.
Series (solar panel): Series solar panels are solar panels that are wired together in a chain, with the positive terminal of each panel connected to the negative terminal of the next. This increases the system’s voltage and output.
Spillage test: A spillage test is a procedure that determines if combustion gases can escape into a home from an appliance. It is performed by a competent person with the appliance in situ and under test procedures.
Specific Humidity: Specific humidity is the ratio of the mass of water vapor to the total mass of air in a given volume, usually expressed in grams of water vapor per kilogram of air.Humidity levels can vary greatly depending on factors such as temperature, location, and weather conditions. High humidity levels can make the air feel muggy and uncomfortable, while low humidity levels can lead to dry skin, irritated respiratory passages, and static electricity buildup. Maintaining optimal humidity levels indoors is important for human comfort, as well as for preserving the integrity of materials and preventing mold growth.
T
Technical monitoring: Refers to the process of verifying and ensuring that energy efficiency measures installed under the ECO scheme are of the required standard, compliant with regulations, and effectively contribute to reducing energy consumption and carbon emissions. It is an essential part of ensuring that the ECO scheme meets its objectives of improving energy efficiency for vulnerable households and reducing carbon emissions across the UK.
Traditional built: A traditional built home is a home built before 1919 using solid wall construction methods and materials, and that is characterized by its “breathable” construction.
Tundish: A tundish is a device that allows water to drain from a heating system when pressure becomes too high. It’s a crucial component of unvented hot water systems and boilers
U
UPVC: Stands for Unplasticized Polyvinyl Chloride, is a low-maintenance building material used as a substitute for painted wood, mostly for window frames and sills when installing double glazing in new buildings, or to replace older single glazed windows.
V
Volatile organic compounds (VOCs): Are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors.
Voc’s can be found in household cleaning items, packaging, plastics, floor coverings. The list can be quite exhaustive. Below are a few included VOC’s
- formaldehyde (resins for building materials)
- vinyl chloride (making of plastics (PVC), floor coverings and consumer goods)
- ethylene glycol (ink, pens, paints)
- isopropyl alcohol (making of cosmetics, pharmaceuticals, perfumes, dye solutions, antifreezes, soaps)
- hexanal (used as a flavouring in food industry and as a fragrance in perfumes)
- carbon disulphide (used in the manufacturing of viscose rayon and cellophane. Also present in varnishes, solvents, and insecticides)
Vapour Barrier: A material used to prevent the passage of water vapour through walls, ceilings, or floors.
Ventilation: The process of exchanging indoor air with outdoor air to control humidity levels and remove indoor pollutants.
W
Waterproofing: The application of materials or coatings to prevent water from penetrating building materials or structures.
Water Damage: Any harm caused to a building or its components due to the presence of water, such as leaks, flooding, or excess moisture.
Water Vapour: Water vapour is water in gaseous instead of liquid form. It can be formed either through a process of evaporation or sublimation. Unlike clouds, fog, or mist which are simply suspended particles of liquid water in the air, water vapour itself cannot be seen because it is in gaseous form.
Z
Zoning: A way of dividing a building into different areas (or “zones”) where the temperature can be controlled independently. Instead of heating the entire house to the same temperature, each zone can have its own thermostat and settings, improving comfort and energy efficiency.