Key information about data required for building decarbonisation projects.
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For decarbonisation projects, it is best practice to design new and updated measures based on an understanding of how the building is actually operated and consumes energy. Energy and building data give a good understanding of baseline consumption and use. Building information will also inform potential design decisions in terms of technical measures that are feasible or desirable. There are a number of areas that will help you to understand the basic terminology.
This is a rundown of the basic terminology you will need to know.
Energy data
Understanding how much energy buildings are using and what it is being used for is vital for delivering building decarbonisation projects. Potential energy and financial savings will be calculated and support specification and design of new equipment.
Energy data for fuel consumption
The most basic energy data required is the amount of fuel or electricity consumed by the building and its occupants.
Electricity (kWh)
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The standard unit for monitoring and billing electricity consumption is kilowatt hours – commonly written as kWh.
Gas (kWh, m3, ft3)
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Gas consumption is monitored and billed in kilowatt hours (kWh), however as gas is delivered as a fuel, the metering (the recording of how much passes through the meter) is either in cubic metres (m3) or cubic feet (ft3). The units will be clearly marked on the meter.
The volume of gas is converted to kWh through a formula, which you will find on the invoices from your gas supplier. This takes the volume of gas used and applies the ‘calorific value’ to determine the amount of energy (in kWh) provided by that volume of gas.
Oil (l)
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Oil is usually delivered via tankers and does not have the same metering as electricity or gas. The dates of delivery and volume (in litres) should be recorded to provide a measure of how much is being consumed.
Oil flow meters can be installed and are widely available, which measure the volume of oil flowing through a pipe, but they are not commonplace. Oil tanks may also have a level sensor or ‘gauge’, which displays the level of oil remaining in the tank and can be used to support consumption tracking. It can be difficult to take accurate readings from these.
Biomass (tonne)
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Biomass can refer to any biological material used as a fuel, but for use in buildings this is usually either wood chips or wood pellets. These are delivered via a lorry.
As biomass is a solid fuel, it is not metered like gas or oil. Biomass is charged by the weight delivered, normally in metric tonnes. Keeping records of the weights delivered and the relevant dates allows consumption to be monitored.
Locating energy data
It can be helpful to take photographs of meters, including for each reading display, so you can later confirm the reading. This will also allow you to match you meter serial number to the relevant invoices.
Electricity (billing) meters
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All sites with an electricity supply will have an electricity meter, also known as a billing meter. Electricity invoices are derived from this meter data.
Most electricity meters now have a digital display, and pressing a button on the meter will provide different information available. Care should be taken when reading meters as they can display multiple consumption readings. Though meters are varied, this can include:
- Total or Rate T: total readings since the meter was installed.
Some electricity meters, particularly at larger sites, may give readings in “kWh x 10” – this means the consumption in kWh is 10 times larger than the reading on the display. This will be clearly marked on the meter where applicable.
Gas (billing) meters
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Gas meters normally show a reading in cubic metres (m3); however, some meters will display readings in cubic feet (ft3).
Electricity (generation) meters
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Sites that have electricity generation equipment installed, typically solar PV panels or Combined Heat and Power (CHP) plants, will have a meter attached to the generation equipment. This measures how much electricity, in kWh, the equipment produces.
The electricity generated will be used on site and ‘displaces’ grid electricity, reducing the amount the site imports from the grid. If more electricity is generated than is needed, the site will export electricity until demand equals or exceeds generation again.
CHP and newer solar PV panel installations (2020 onwards) will likely have export meters, allowing export and on-site demand to be calculated. Older solar PV panel installations may not have an export meter, so it can be difficult to determine if the site ever exports electricity.
The total electricity consumption of a site with on-site generation is calculated as below:
Total consumption = billing meter total + (generation meter total – export meter total)
If there is no export meter, you will normally need to assume no electricity is exported. If half-hourly or smart meter consumption data is available, you can review this to see if the import of electricity ever reaches zero, as this would happen when electricity is exported. This does not provide a complete picture of consumption, but it can help to understand the export position:
- If the half-hourly / smart meter date does not show any times when imported electricity was zero, then no electricity was exported.
- If the half-hourly / smart meter date does show times when imported electricity was zero, then it is likely some export occurred, but this does not calculate how much.
With large data sets on demand and generation, you may be able to calculate how much electricity was exported in the absence of an export meter, however it is usually fairly small and shouldn’t affect your decarbonisation project.
Sub-meters
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Electricity sub-meters are not used by energy suppliers, but they may be installed to support energy monitoring within the organisation. These measure electricity consumption on a specific circuit and allow usage within areas to be metered separately to the rest of the building.
There are many reasons why sub-meters may be installed, including to:
- monitor usage on a floor or room/area basis.
- monitor usage, where a particular building/floor/area of a building is leased to a third party (allowing electricity costs to be re-charged accurately).
- monitor usage of a particular piece of equipment, such as an air conditioning unit or electric vehicle (EV) charging point.
It is important to understand what circuit(s) the sub-meter covers, and what equipment/areas are served by those circuits, when interpreting the data they produce.
Gas sub-meters
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Sub-metering is less common for gas than for electricity, but it has the same role in measuring consumption within a specific area or for a specific use.
Automatic meter reading (AMR)
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An automatic meter reading (AMR) device automatically provides regular meter readings to the energy supplier and allows accurate bills to be calculated. AMR is available for both electricity and gas supplies and is mandated for large consumers (over 100,000 kWh of electricity, and 732 MWh of gas).
Where an AMR meter is installed, it removes the need for both manual meter readings and estimated bills.
You may also be able to access more detailed consumption data, such as a ‘half-hourly’ data set, showing how much energy is consumed in each half-hour time period. This information can improve the accuracy of different energy audits/surveys (covered later in this module) and help shape decarbonisation projects.
Specific metering arrangements vary between suppliers and reflect different supply and meter types. If you are unclear about your building(s)’ metering arrangements, it is recommended you speak to your electricity supplier in the first instance, and they can help you to access what energy data is available.
Smart meters
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Similar to AMR, a smart meter will automatically take meter readings and provide these to your energy supplier for billing purposes. However, smart meters can provide high-frequency (multiple readings per minute) or near-instantaneous consumption data. The additional details on energy consumption patterns can be useful when determining how much energy particular assets are using and peak loads.
Energy database
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Large amounts of energy data can be created by a single site. Many organisations have an energy database to support its storage and use. Energy databases can undertake a range of functions to support energy management activities and can typically provide:
- Electronic billing information from the supplier – removing the need for paper invoices.
- Energy consumption data (e.g. half-hourly energy profiles)
- This may be received monthly, aligned with a billing cycle, or a ‘day +1’, where consumption data from the previous day is available (more common where half-hourly data is being provided).
- Reports on energy usage, including across multiple sites or time frames.
- Consumption monitoring and issuing alerts when defined limits/parameters are exceeded (e.g. more than 100 kWh are used in a 24-hour period).
Electricity and gas bills/invoices
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Energy invoices can contain a lot of different information and though there are presentational differences between suppliers, there are a lot of commonalities in the information provided. Below is a summary of the common types of information available, however please be aware this can vary depending on your supplier, the meter/supply type (i.e. a half-hourly or non-half hourly supply), and the contracting arrangements in place.
- The energy consumption (in kWh though calculated from m3 or ft3 for gas) over the billing period – typically a calendar month but smaller sites may be billed quarterly – and the unit charge for this consumption.
- Details of whether the invoice is based on:
- ‘Actual’ readings – manual readings or via AMR.
- ‘Estimated’ readings (sometimes abbreviated to ‘e’ next to the reading or consumption figures) based on expected consumption levels.
- The breakdown of other charges including:
- Standing/daily charges – based on the number of days that month, which can include metering and supply/distribution-related charges.
- Climate Change Levy (CCL) and VAT.
- CCL is payable unless the energy supply usage or level of consumption qualify for an exemption.
- VAT is charged at 20% unless the reduced rate of 5% is qualified for, again related to the energy supply usage or level of consumption.
- You will need to notify your supplier to benefit from these reductions.
- A commission or management charge, dependent upon your contracting arrangements.
- Depending on the contract type in place, there can be a range of other costs covering risk, network charges, and environmental levies.
The above is not intended as a detailed guide to energy billing practices – if you are unsure about details on your bills, it is best to discuss these with your supplier.
Building information
To develop a decarbonisation project, it will be necessary to design new measures based on an understanding of how the building is configured and used. There are a number of items that can help in this in forms of registers and surveys.
Asset register
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An asset register records the details of the relevant equipment present in the building. Organisations will often record different asset types on a number of registers. The building or maintenance asset register normally focuses on the assets that provide building services, such as heating, cooling, and lighting.
The asset register is a useful starting point for identifying the energy-consuming equipment in the building, from which their key characteristics can be identified; for example, the thermal output of a boiler. The asset register will also provide details of the air conditioning systems installed, which will help to identify the refrigerant gas it contains, which is needed to quantify the climate impact from its fugitive emissions.
Floor plans
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Often stored electronically, although older buildings may still have paper drawings, floor plans show the layout of the building’s structure and dimensions in two dimensions. The exact details can vary, but floor plans typically show the layout of walls, the location of openings such as doors and windows, and the location of where electrical and mechanical services are located, for example, the plant room for heating systems.
Floor plans can be out of date and a site walkover or survey (covered later in this module) will identify where the building no longer reflects the plans.
Diagrams/schematics
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Some of the core systems in the building will have diagrams or schematics associated with them. This includes the electrical, heating, cooling, and HVAC systems.
Schematics are technical drawings that show how the components in the system are connected and arranged. For example, the layout of pumps, values, and radiators on a heating circuit, or the layout of light fittings and switches on a lighting circuit. Importantly, schematics do not show the physical layout or dimensions of the system – for example, they do not show where switches are or how long a cable/pipe is.
Schematics show how the components relate to each other in their layout – such as how many light fittings are on a circuit, or how many heating circuits are fed by a particular boiler. This type of detail is important for designing any replacement equipment. These details cannot be easily determined from a site survey, as the wires/pipes, etc are not easily accessed, and it is time consuming or highly impractical to determine their connections.
Condition surveys
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Condition surveys, as the name suggests, tell you about the condition of a building – that is whether the fabric and key infrastructure of a building is in a good state of repair or not. The scope of the surveys may be customised. Some may focus on individual features across multiple buildings (for example, roof condition surveys), but typically, these are broad and look at the building as a whole.
Condition surveys will typically grade the condition on an A to D scale – A being good and working as expected, D being bad and either close to or already failing. Condition surveys also indicate the priority of the issues, often graded on a 1 to 4 scale, where 1 requires urgent attention and 4 is a longer-term issue (often more than five years out). The survey will be clear on what scale is being used and what the ratings mean.
Maintenance records
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Organisations will hold a record of the maintenance activities that have been performed on a building. This will include both ‘planned’ activities, such as annual services on equipment, as well as ‘reactive’ activities undertaken in response to an issue arising.
These records can help to inform a decarbonisation project by indicating whether existing equipment has known issues, is approaching the end of its useful life, or more generally what condition it is in. For example, if a particular piece of equipment has repeatedly failed and required reactive maintenance, or it has not been serviced regularly, there can be a risk it will not work as designed and may need replacing for the decarbonisation project to be successful.
Health and safety records
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Decarbonisation projects will need to be undertaken in a manner that ensures the safety of those working on the project, as well as other building users. The organisation will have a health and safety policy as well as specific processes/requirements for how works on site are undertaken. This can include measures such as ensuring any visitors ‘sign in’ to a visitor book when arriving, to ensure it is known who is on site at any given time.
The organisation, as well as any visitors/contractors working on a project, should know their responsibilities for managing health and safety risks. This e-learning is not intended as a guide to managing these issues, so if you have any questions, these should be directed to your organisation’s health and safety lead. Further guidance is also available from the Health and Safety Executive.
Asbestos register
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Historically, asbestos was widely installed in buildings to provide insultation and fireproofing. However, it is now known to be carcinogenic (cancer causing) and was banned from use in new products from the early 1990s. It remains present in many buildings and if left undisturbed, its risks can be managed effectively.
However, work on buildings containing asbestos risks disturbing the material and releasing its fibres into the air, and this presents a health and safety risk to building users, and in particular for the those carrying out the work.
An asbestos register is a record of where asbestos is known to be present in the building – this will form part of a wider Asbestos Management Plan.
If asbestos is present in an area that will be disturbed by the project, the risks will need to be managed closely. One option is to remove the asbestos. There are strict requirements on how this is done, and these works can be expensive. Identifying where asbestos is present early on will help meet health and safety requirements and also ensure the full costs and timings of the works are understood.
Please note: This is not intended as a comprehensive guide to managing asbestos risks – if you have any questions or concerns about asbestos, you can seek further guidance from your organisation’s Health and Safety lead, and the Health and Safety Executive provide further guidance: Asbestos – HSE.
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