How HEAS Works

Summary

Two types of data are entered into HEAS. Bills are entries where there is both a consumption and financial component, for example the first line. Bills will typically come from the supplier of the energy source. Readings result from going to the meter and recording the current value. HEAS is capable of accepting times to the accuracy of minutes. This is normally available for readings but is typically not presented for bills. For consumption analysis, the difference in meter readings is divided by the time between the readings to calculate the value for the period. Costs are treated similarly, but it is usually impossible to obtain data between bills so that fluctuations with time are not calculated as accurately.

Bills at Start and End of the Year

Date	Reading	Cost	Graph
31/Dec/2004	1000	40.00	1
01/Jan/2006	1210	40.00	1

This graph shows how the total consumption for the year is split by linear interpolation over the twelve month period. The table shows that total consumption for the period was 210 and the average per month is 210/12 or 17.5. The bars for the 31 day months are taller than those for the 30 day months which in turn are taller than those for February. The calculation for 31 day months is 31/365 of 210 = 17.84. 30 day months consume 17.26 and February's figure is 16.11.

Add bills for each Quarter

Date	Reading	Cost	Graph
01/Apr/2005	1030	30.00	2
01/Jul/2005	1110	60.00	2
01/Oct/2005	1180	80.00	2

The second graphic shows the consumption graph generated when bills for each quarter are added.

Add readings for the missing Months

The graphic above shows the consumption graph generated when readings are added for the missing months. Note that the reading dated 16th March covers one and a half months: two thirds will be allocated to February, and the other third will be added to the figure for March, along with the reading made on April 1.

The general rule is that the more readings or bills are entered, the closer the graph generated will be to the actual consumption. Taking readings close to the start or end of a period will also help the accuracy of the graph.

Estimated Carbon Dioxide Emissions

The graphic shows the calculated carbon dioxide equivalent of the consumption of this fuel. Note that the fuel became more carbon dioxide efficient after July 1, and hence the calculated emissions halved.

Graph based on partial readings

This graph is based on readings that started in late February 2006 with the last in early July

Consumption defaults to zero when there are no readings available.

It is not necessary to wait for the start of a year to gain useful results from HEAS.