The seven-degree method assumes the following: (i) gas temperature in the gas meter is 7 °C; (i) nominal delivery pressure (pressure) is 28 millibars; (i) Atmospheric pressure is 1.01325 bar. This research has shown that the actual gas temperature in the gas meter can significantly vary from the assumed value of 7 °C. The in the seven-degree method assumed gas temperature of 7 °C can, in extreme situations (depending on the location of the gas meter in the house), in average deviate more than +5% (based on absolute temperature). By the assumption that the gas pressure is constant (28 millibars) and the atmospheric pressure is 1.01325 bars, an error in the volume conversion is introduced which is significantly smaller than the "temperature error". An important advantage of applying the seven-degree method for domestic end users using a diaphragm gas meter is that the gas meter reading corresponds with the converted volume to normal conditions. The administrative process is rather simple and an administrative correction is not necessary. The measurement errors can be significantly reduced, if the average gas temperature (7 °C) as assumed in the seven-degree method, is changed to a temperature closer to the actual average gas temperature (for instance 15 °C). In this case, the average measurement error for all types of houses / households is relative small. However the differences between the households will in this case remain. An administrative correction to convert to normal m³ is in this case necessary. A correction is also necessary for conversion from the supply pressure (from 28 millibars) to atmospheric pressure. Based on the results of the research performed by Kiwa Gas Technology, the following main conclusions can be drawn: 1. The size of the difference between the measured quantity of gas (with application of the seven-degree method) and the actually delivered gas quantity is mainly determined by the location of the gas meter in the building and the location of the gas meter (temperature effect). 2. Based on field research in 26 houses in the heating season 2007/2008 a estimation of the measurement error caused by the temperature effect in the application of the seven-degree method for "standard" year was made. The measuring errors in the houses in this study are in all cases unfavourable for the end customer and amounts from 1.6 to 4.6% annually. 3. The measurement deviation due to the temperature effect depends on the type of house. 4. Based on the results of field studies and an estimated distribution of house types in the housing stock in Netherlands it is concluded that the total measurement error for all domestic gas customers in the Netherlands amounts 275 to 415 million m³ per "standard" year (2.6 to 3.9%), unfavourable for the end customer. 5. The (supposed) gas pressure also determines the accuracy of gas volume measurement. The difference between the mean delivery pressure and atmospheric pressure compared to the in the seven-degree method assumed delivery pressure (28 mbar) and atmospheric pressure (1.01325 bar) is relatively small. The measurement error due to the delivery pressure is estimated at less than + / - 0.2% in the advantage or disadvantage of the customer. For the atmospheric pressure the error is also small (<0.2%), however systematically in favour of the customer.