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  • Energy Savings Calculator

    'Choices' Energy Calculator

    Are you looking to make your home more energy-efficient?

    With 'Choices' Windows, you can reduce the energy loss of your home by up to 40%. Use our energy calculator to help you understand how much energy you could save with our range of energy-efficient windows.

    Leveraging modern technology to create a more sustainable world

    At Sandwich Glass Ltd we install CWG 'Choices' brand windows. CWG use the latest technology and techniques to ensure that their 'Choices' windows and doors are energy-efficient to help create a more sustainable living environment. Sandwich Glass Ltd are committed to being an active player in the fight against climate change and our selection of energy-efficient windows and doors are the perfect solution for energy-conscious homeowners.

    See what you can save

    With our energy efficiency calculator, you can easily see how much energy and carbon Choices products will save you. Make an energy-efficient choice today and reduce your energy consumption with Sandwich Glass Ltd.

    * A British detached house has approx 25m2 glass area.

    How do we calculate the energy savings in Yearly kWh?
    We start by calculating your energy consumption in relation to your current windows and selected region. Using this equation:

    (U-Value of current windows x Glass area of home) x Entire year's recorded degree days for selected region x (24/1000) = Current energy consumption

    We calculate your energy consumption in relation to the selected CWG windows and selected region. Using this equation:

    (U-Value of new 'Choices' windows x Glass area of home) x Entire year's recorded degree days for selected region x (24/1000) = New energy consumption

    To get the total savings, we calculate the difference between the new energy consumption and the old energy consumption, Using the following equation:

    Current energy consumption - New energy consumption = Total energy savings*

    *Please note, we are only calculating the difference in energy consumption between your current windows and CWG windows, the energy efficiency of your entire home is not required.

    *How do we calculate the yearly CO2 Savings?
    Because we know the energy savings, we can multiply the energy savings by the amount of C02 created per kWh. Using this equation:

    Total energy savings x CO2 generated per kWh = Total CO2 savings

    **How do we calculate Savings?

    Financial Savings are calculated by multiplying the kWk Savings by £0.34 per kWh, as published by the Energy Price Guarantee From 1 October 2022.


    Degree Days for selected UK region are for the year 2022 and based on a 15.5 Deg internal temperature. The Degree days data source can be viewed online https://www.enmanreg.org/freedd/uk-degree-day-data/

    The function we used for calculating energy energy consumption can be found a https://www.open.edu/openlearn/nature-environment/energy-buildings/content-section-2.4.2

    Data for average amount of CO2 created per kWh can be found here https://bulb.co.uk/carbon-tracker/#:~:text=With%20an%20average%20supplier%2C%20annual,kg%20per%20kWh%20of%20gas

    Sandwich Glass Ltd reserves the right for errors in weather data.