GB2102964A

GB2102964A - Meters

Info

Publication number: GB2102964A
Application number: GB08222094A
Authority: GB
Inventors: Narotam Singh Grewal
Original assignee: Satchwell Controls Ltd
Current assignee: Satchwell Controls Ltd
Priority date: 1981-07-30
Filing date: 1982-07-30
Publication date: 1983-02-09

Abstract

A meter providing data for use in checking fuel consumption of a building heating system comprising: means setting a reference temperature (9); timing means (5); means for reading the temperature outside the building at predetermined intervals (1, 3); means for accumulating the values of the products of any difference, in a given sense, between each outside temperature reading and the reference temperature, and the duration of the preceding interval (7, 11); and means for producing an output representative of the value of the accumulated products (13). <IMAGE>

Description

SPECIFICATION Meters This invention relates to meters.

In order to keep a check on the efficient use of fuel by a building heating system it is common practice to use so-called 'Degree Day Reports' issued monthly by the Gas Council. These reports contain data giving an indication of the amount by which, and the time, that outside temperature has been below a reference temperature of 1 5.50C over a given period. From this data an estimate of the amount of fuel which should have been required to maintain the temperature inside the building at a predetermined temperature above the reference temperature can be obtained. By comparing this estimate with actual fuel consumption an indication astro how efficiently the consumed fuel has been used may be obtained. The data in the reports can, of course, also be used in other ways, for example, for predicting future fuel consumption.

It is an object of the present invention to provide a meter which provides an output capable of use in a similar manner to the above mentioned Degree Day Report data.

According to the present invention there is provided a meter comprising: means for measuring the temperature outside a building; means setting a reference temperature; timing means; means for reading the outside temperature at predetermined intervals determined by the timing means; means for accumulating the values of the products of any difference, in a given sense, between each said reading of the outside temperature and the reference temperature, and the duration of the preceding said interval; and means for producing an output representative of the value of the accumulated products.

Preferably each said interval is of equal duration and has a duration not greater than ten minutes.

It will be appreciated that a meter in accordance with the invention may be used to provide data relevant to the operation of a cooling or heating plant for a building according to whether the given sense corresponds to temperatures above or below said reference temperature.

Normally the readings of outside temperatures are spot readings, but may alternatively be averages of readings taken over the preceding said interval.

The means for producing an output suitably comprises visual display means.

A meter in accordance with the present invention may suitably comprise an appropriately programmed microprocessor, together with means for measuring the temperature outside a building.

A meter in accordance with the invention may suitably be incorporated in control apparatus for regulating the operation of apparatus for cooling and/or heating a building, in which case the meter outside temperature measuring means, timing means, and, if present, microprocessor, may also form parts of the control apparatus.

Apart from providing data which can be used in a similar manner to the data contained in Degree Day Reports, the data provided by a meter in accordance with the invention has certain advantages over Degree Day Report data.

The data in Degree Day Reports are compiled from temperature measurements made at a few selected locations throughout England and Scotland. Thus the data in these reports may not be strictly applicable to the particular building in which a heating system is located, especially where the building is subject to somewhat special conditions due, for example, to it being in a particularly exposed or sheltered location. A meter inn accordance with the invention clearly can provide data uniquely relevant to the locality in which the meter is used.

Furthermore, because of the difficulty of obtaining large numbers of temperature measurements at frequent intervals, the data in Degree Day Reports are compiled by measurement of the maximum and minimum temperatures occurring during each twenty-four hour period, and various empirical formulae are used to take account of the fact that no measurement of the actual times in a twenty-four hour period for which any particular temperature is maintained is taken. A meter in accordance with the invention clearly computes data which takes full account of the times for which temperatures are maintained.

One meter in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a block schematic diagram of the meter; and Figure 2 is a diagram illustrating the operation of the meter.

Referring to Figure 1, the meter includes a temperature measuring device 1, such as a thermistor, arranged to provide an electrical signal representative of the temperature To outside a building in respect of which data comparable to the Degree Day Report data supplied by the Gas Council is required.

The output of the device 1 is sampled at regular frequent intervals t (e.g. one to ten minutes) by a sampling circuit 3 under the control of a timing circuit 5.

Each sample is fed to a data processing circuit 7 wherein it is discarded if it is representative of a temperature above a temperature TR set by a reference temperature circuit 9. If the reference temperature is greater than the sampled temperature, the processing circuit 7 produces a signal (TAT0)t representative of the product of the difference of the reference and sampled temperature and the sampling interval. Each such output of the processing circuit 7 is fed to a counter circuit 11 where it is added to the sum of the preceding outputs.

The resulting signal (TRTO)t is utilised to drive a display device 13 to produce a visual indication of the output signal of the counter circuit.

The counter circuit 1 3 suitably comprises a degree minute counter stage coupled with overflow counters provided degree hour and degree day counts, the display means producing a corresponding display.

It will be understood that the processing circuit 7 and counter circuit 11 will normally operate with digital signals in which case the associated circuits 1, 3, 5 and 9 will also produce digital outputs.

The reference temperature may be fixed, for example at a value of 1 5.5 C to give data more comparable to that given in the Gas Council reports, or be adjustable to give data with respect to a selected reference temperature. It is pointed out in this connection that the value of 1 5.50C used for the Gas Council data is chosen on the basis that 1 8.30C is a comfortable inside temperature for a building for normal purposes, and the discovery that, due to the fact that all the warming of a building is not supplied from its heating plant, the variation of fuel consumption required to maintain inside temperature at 1 8.30C is more nearly proportional to the difference between outside temperature and 1 5.50C than to the difference between outside temperature and 1 8.30C. Thus where an inside temperature other than 1 8.3 OC is required, or the building is not used for normal purposes, a different reference temperature will be required.

Figure 2 illustrates successive outputs (TRTo)t passed to the counting circuit 11 from the processing circuit 7 for a variation of outside temperature To as indicated by the line A in Figure 2, for a sampling interval t of one minute, and a reference temperature TR of 1 5.50C.

The use of a sampling interval of one minute reduces the amount of computation required by processing circuit 11, but of course a different sampling interval may be used, if desired.

However the sampling interval will not normally be so long that a change of outside temperature of more than one degree is likely to occur between successive samples.

It will be appreciated that at least the circuits 7 and 11 may be constituted by a suitably programmed microprocessor, and that the microprocessor may form part of a control apparatus for regulating the operation of a heating plant for the building, as may also other components of the meter such as the outside temperature measuring device 1, and the timing circuit 5.

It will further be appreciated that the microprocessor may be programmed to cause the display device to display data other than the total degree hours, days and minutes since initiation of operation of the meter, e.g. to display the degree days, hours and minutes over a selected period.

It will further be understood that a meter according to the invention may be arranged alternatively, or additionally, to provide data in respect of variation of outside temperature above instead of below a reference temperature, such data being of use in checking the operation of building cooling plant. For cooling operation data the reference value will normally be the desired inside building temperature, not slightly below the desired inside building temperature, as explained above in respect of heating operation data. In a meter performing both functions, the degree minutes in respect of heating and cooling operations can be summated in a common counter and/or individually accumulated in two separate counters.

Claims

1. A meter comprising: means for measuring the temperature outside a building; means setting a reference temperature; timing means; means for reading the outside temperature at predetermined intervals determined by the timing means; means for accumulating the values of the products of any difference, in a given sense, between each said reading of the outside temperature and the reference temperature, and the duration of the preceding said interval; and means for producing an output representative of the value of the accumulated products.

2. A meter according to Claim 1 wherein each said interval is of equal duration.

3. A meter according to Claim 2 wherein each said interval has a duration not greater than ten minutes.

4. A meter according to any one of the preceding Claims wherein the readings of outside temperature are spot readings.

5. A meter according to any one of Claims 1 to 3 wherein the readings of outside temperature are averages of readings taken over the preceding said interval.

6. A meter according to any one of the preceding Claims wherein said means for producing an output comprises visual display means.

7. A meter according to any one of the preceding Claims wherein at least said means for accumulating comprises a microprocessor.

8. A meter substantially as hereinbefore described with reference to the accompanying drawings.

9. A control apparatus for regulating the operation of apparatus for cooling and/or heating a building incorporating a meter according to any one of the preceding Claims.

1 0. A control apparatus according to Claim 9 wherein the meter outside temperature measuring means and timing means form parts of the control apparatus.

11. A control apparatus according to Claim 9 or Claim 10 when dependant on Claim 7 wherein said microprocessor forms part of the control apparatus.