# “Better Than The Standard”

 In accordance with the described methodology, the Bygone Collection of sash windows has been simulated under the BFRC calculation method. The Bygone window loses just 20KW / per square metre / per year.

## Putting this into Perspective

In order to put this into some meaningful numbers we must first set the calculation criteria.

This paper is calculating the costs and CO² during the winter months, when heating would be required. For most households, our figures show that an average household has their heating on for, a period of 191 days, just over 6 months, taking into account increased usage for the colder days of the season, and shorter lengths of time for the Autumn / Spring days, and the difference between week days and weekends, and for an average of 8 hours a day, with a temperature difference between outside and inside of 15 degrees

It is also necessary to understand how the heat loss is calculated. What does W/m2K actually mean, let me explain.

A Watt is a unit of measure for energy, it is 1 Joule per second. is the area of the window, width x height, and Kelvin is the difference in temperature from the inside to the outside, the rest is just mathematics.

## The Energy Loss Explained

To benchmark the Bygone window, lets first calculate how much money is lost in heat through a old single glazed timber window at 5.8W/m²K

Using the CEN standard size window as the standard size this would mean that the total heat loss would be 242 KW

(5.8 joules per second x 1.82m² x (191x8) x 15 =241.94KW )

Our average order quantity is 7 windows, and therefore the heat loss through the windows of an average house would be in the region of 1,693.58KW

(242KW x 7 = 1,693.58KW)

## The costs

Based upon an average cost of 10 pence per KW (1000 Watts) per hour, the average single glazed timber sash window would lose the equivalent of £24.20 each year.

(241.94KW x £0.10 = £24.20)

However most boilers are only 70% to 80% efficient, consuming energy in the boiler itself and therefore the output cost should be factored by an average 25%

Meaning the average property with 7 timber sash windows, spends approximately £211.25 every year replacing the heat that is lost through the windows.