NO344076B1

NO344076B1 - Limiting arrangement of peak power of heating energy

Info

Publication number: NO344076B1
Application number: NO20180440A
Authority: NO
Inventors: Hannu Koskela; Jukka Koskela
Original assignee: Smart Heating Oy
Priority date: 2017-04-03
Filing date: 2018-04-03
Publication date: 2019-09-02
Also published as: SE1850363A1; NO20180440A1; FI20175308A; FI127418B; SE543114C2

Description

An arrangement for limiting peak loads in heating energy consumption

The invention relates to a load limiting device to be utilized in limiting peak loads in heating energy consumption, a load limiting arrangement, a load limiting method, and a computer program product to be utilized in the load limiting method.

Prior art

Housing associations are normally invoiced for district heating on the basis of two items: a basic fee and an energy unit fee. The basic fee is normally based on time, and it is generally expressed in €/year or €/month. Payment for energy is made according to the consumption, based on the energy unit fee. The energy unit fee for district heating indicates the price for district heating energy per one energy unit, generally €/MWh or €/kWh.

The basic fee is normally not affected by the amount of district heating energy paid, but it is determined at least partly by either the measured peak load or the district heating water flow rate m<3>/h (volume water flow rate, contract water flow rate, subscription water flow rate) during the peak demand. The basic fee may be based on other factors as well, such as the amount of cooling in district heating. However, the peak load is normally the greatest single factor determining the basic fee. The purchaser and the supplier may agree upon a calculated level for the peak load, or it may be determined according to the actual peak load measured. This peak load may be checked, for example annually, by either the supplier or the purchaser. Some district heating companies have an annual automatic check on the peak load on the basis of the highest load per hour measured within a year, that is, the highest average district heating load per hour.

The share of the basic fee in the district heating bill is normally smaller than the share of the energy unit fee. However, the basic fee may be high as well, in the largest apartment buildings for example 10,000 to 20,000 € per year. Savings in the energy unit fee can be achieved by reducing the energy consumption of the building, for example by increasing insulation or by using heat pumps, whereby less energy is purchased. These are normally expensive but profitable measures. Savings in the basic fee are more difficult to achieve, even if the above mentioned measures normally reduce the peak load and thereby the basic fee to some extent as well.

Various arrangements for limiting the heating output of heating systems of buildings are presented in documents DE 19604189, DE 19859364 and EP 2985535.

Figure 1a exemplifies an arrangement 10 of prior art for controlling district heating in a building, to be utilized in various buildings, such as apartment houses. Temperature control in the building is performed by a control device 1 so that the room temperature in different parts or apartments of the building is maintained within a predetermined temperature range. The temperature control device 1 may be a programmable electronic control device comprising a processor for executing control commands and a suitable amount of memory for storing the control algorithm needed for controlling the temperature. Furthermore, the temperature control device 1 comprises various inputs for receiving the required temperature measurement data, and various outputs for controlling at least one valve 4 (reference 1a) of a district heating network 10A, for controlling the heat consumption of the building. The temperature control device 1 may also comprise outputs for controlling valves of a heating system 100A. The temperature control device 1 may also comprise a user interface with a keypad and a display. The heating system 100A which will be mentioned in the description hereinbelow may be, for example, a radiator network, an underfloor heating system, or a liquid circulation system relating to air heating equipment, or a combination of these.

Outdoor temperature is measured by a temperature sensor 2 connected to one input of the control device 1.

The temperature of the water circulating in the heating system of the building is measured by a supply water sensor 3 connected to the pipe of the heating system 100A, at the end next to the heat exchanger. The supply water sensor 3 is connected to one input of the control device 1, via which the temperature value 3a of the water supplied to the heating system is input in the control device 1. By using the measurement value 2a for the outdoor temperature and the measurement value 3a for the temperature of the water supplied to the heating system 100A, the temperature control device 1 is configured to control the valve 4 of the district heating network 10A so that the temperature in the building is maintained within predetermined limit values for the temperature. For adjusting the temperature, the temperature control device 1 transmits a control command 1a to the valve 4. By the control command 1a, the temperature control device 1 may either increase or decrease the flow rate of heating water in the pipe from the district heating network 10A to the building, by changing the setting of the valve 4.

In many cases, the same control device 1 is also used for adjusting the temperature of domestic hot water in the building, in the same way as for adjusting the temperature of the water in the heating system 100A. This adjustment is not shown in Fig.1a.

Figure 1b shows an example in which the peak value 13 for the heating load in the building in a time interval from 12 to 14 exceeds an exemplary limit value 5 for a heating load determining a basic fee, the limit value being 300 kW in the example of Fig.1b. Because the peak load 13 has exceeded the limit value 5 for the basic fee for at least an hour, an increased basic fee to be charged for the building will also apply to a time 11 when the heating load has been lower than the limit value 5 of the heating load set for the basic fee.

In the example of Fig.1b, it is possible to measure the volume water flow rate instead of the heating load of the building in the district heating system. Thus, Fig.1b may illustrate the quantity of district heating water that has flowed from the district heating system through the heat exchanger of the building. In this case, the limit value may be a quantity of district heating water in m<3>, for example per one hour.

In a heating system of prior art, a problem with the heat control may be the determination of the basic fee for the whole year on the basis of a single peak of relatively short duration in the consumption of heating energy. If the peak in the consumption of heating load can be prevented, the saving in the basic fee of district energy is, at best, thousands of euros per year.

Aim of the invention

The aim of the invention is to present a new control method reducing the costs of energy for heating a building, a control arrangement, a load limiting device, and a computer program product to be utilized in the control method.

The aims of the invention are achieved by a control method, a control arrangement, a control device, and a computer program product to be utilized in the control method, by which a momentary peak demand of energy for heating a building is distributed over a period of time longer than the original period of peak load. The invention is used to prevent a single heating load peak of short duration, needed for heating a building, from exceeding a limit value set for changing the basic fee.

The invention has the advantage that it can be utilized in old as well as new buildings, and the utilization of the invention does not require changes in the existing heating control system or heating system.

It is another advantage of the invention that the load limiting device according to the invention can be installed in parallel with an existing temperature control device so that no changes need to be made in the temperature control algorithm applied in the temperature control device.

Yet another advantage of the invention is that the heating load needed for heating domestic hot water can be reduced in connection with the control of the heating system, to boost the control.

Yet another advantage of the invention is that even if the peak load of district heating were limited during a consumption peak, the demand for heating the building can be met within the temperature range set over a longer period of time, because the purchased total amount of heating energy is not changed but merely distributed over more hours after an anticipated load peak.

The method and the apparatus according to the invention are characterized in what will be presented in the independent claims.

The method according to the invention for limiting the heating load of a building, wherein an outdoor thermometer is used for measuring the outdoor temperature and a supply water sensor is used for measuring the temperature of water supplied to a circulating water system, is characterized in that a load limiting device is used for – receiving meter pulses from an energy meter of the building to the load limiting device, reflecting the heating energy consumption,

– computing the average heating load of the building between two successive meter pulses in the load limiting device,

– comparing the computed average heating load with a proactive upper limit set for the heating load, and if the proactive upper limit set for the heating load has been exceeded,

– activating the restricting functions of the valve of at least one district heating network, for reducing the heating load of the building by heating the supply water sensor of at least one circulating water system by means of a heating resistor.

The arrangement according to the invention for limiting the heating load of a building, comprising a temperature control device for the building, an outdoor thermometer, a supply water sensor for measuring the temperature of supply water entering the circulating water system of the building, is characterized in that the control arrangement further comprises a load limiting device which is configured

– to receive meter pulses from the energy meter of the building to the load limiting device, reflecting the heating energy consumption,

– to compute, in the load limiting device, the average heating load consumed in the building between two successive meter pulses,

– to compare, in the load limiting device, the computed heating load with the proactive upper limit set for the heating load, and if the proactive upper limit set for the heating load has been exceeded,

– to take action for limiting at least one valve in the district heating network, for reducing the heating load of the building by heating a supply-water sensor of at least one circulating water system by means of a heating resistor.

The device according to the invention for limiting the heating load of a building is characterized in that it comprises means

– for receiving meter pulses from the energy meter of the building to the load limiting device, reflecting the heating energy consumption,

– for computing the average heating load consumed in the building between two successive meter pulses,

– for comparing the computed average heating load with a proactive upper limit set for the heating load, and if the proactive upper limit set for the heating load has been exceeded,

– for activating the restricting functions of the valve of at least one district heating network, for reducing the heating load of the building by heating the supply-water sensor of at least one circulating water system by means of a heating resistor.

The computer program according to the invention is characterized in that it comprises code means which are configured

– to compute, in the load limiting device, the average heating output consumed in the building between two successive meter pulses,

– to compare, in the load limiting device, the computed average heating load with a proactive upper limit set for the heating load, and if the proactive upper limit set for the heating load has been exceeded,

– to activate the restricting functions of the valve of at least one district heating network, for reducing the heating load of the building by heating a supply-water sensor of at least one circulating water system by means of a heating resistor.

Some advantageous embodiments of the invention are presented in the dependent claims.

The basic idea of the invention is the following: Using the device according to the invention for limiting the heating load, it is possible to prevent an increase in the basic fee of district energy for a building because of a short-term peak in the heat consumption. The load limiting device according to the invention is used to limit the district heating intake of a building, preferably only from the beginning of a foreseeable short-term peak load. The peak load is foreseen by the load limiting device when a proactive upper limit, predicting a load peak and set in the load limiting device according to the invention, is exceeded.

After the consumption of thermal energy in the building has been decreased by load limiting measures according to the invention to a predetermined load level, the load limiting device reduces the load limiting measures, preferably gradually. Thus, when the load limiting device according to the invention is used, the district heating energy needed for heating is thus distributed over more hours after the beginning of a foreseeable load peak. Thus, for each hour when load limiting is applied in the building, the average heating load will remain on a level that does not cause an increase in the basic fee. Nevertheless, the amount of heating energy may preferably be similar to the amount that would have been consumed without using the load limiting device according to the invention.

In the control arrangement of the invention, the meter pulses transmitted by the district heating energy meter of the building are received by the load limiting device according to the invention. One meter pulse corresponds to an amount of energy determined for the system. By applying the time between two successive meter pulses, the load limiting device according to the invention computes the average heating load for the time between the pulses. If the result of the computation is that the heating load has exceeded a proactive upper limit predetermined for the control, or if exceeding is foreseeable on the basis of a trend, the load limiting device according to the invention triggers measures for limiting the load. The strength and promptness of the load limiting measures preferably increase upon approaching the limit value for the basic fee specific to the building.

The load limiting device according to the invention can be installed in parallel with a temperature control device already existing in the building so that the operation of the temperature control device is not changed. In the control arrangement according to the invention, the heating load of the building is preferably adjusted by heating the supply water sensor of at least one circulating water system in the building by means of a resistor. The adjustable circulating water system may be either a heating system or a hot water supply system. Thus, according to the invention, the temperature control device controlling said circulating water systems of the building receives a corrected measurement value higher than the actual value, and, in response, reduces the flow of hot water supplied from the district heating network to the heat exchanger of the building.

In a preferred embodiment of the invention, the load limiting device according to the invention is electrically connected to such an input of the temperature control device in the building, via which the operation of the temperature control device can be controlled so that the flow of heating water from the district heating network to the heat exchanger of the building is reduced.

In a preferred embodiment of the invention, the load limiting device according to the invention can also be equipped with the functions of the actual temperature control device, whereby the existing temperature control device can be replaced by the load limiting device according to the invention.

In the following, the invention will be described in detail. In the description, reference will be made to the appended drawings, in which

Fig. 1a exemplifies a control arrangement for a prior art heating system with water circulation;

Fig. 1b exemplifies the load behaviour of the control arrangement for the heating system with water circulation, in relation to time;

Fig. 2a exemplifies a control arrangement for a heating system with water circulation according to a first embodiment of the invention;

Fig. 2b exemplifies a control arrangement for a heating system with water circulation according to a second embodiment of the invention;

Fig. 2c exemplifies a control arrangement for a heating system with water circulation according to a third embodiment of the invention;

Fig. 2d exemplifies a temperature sensor to be utilized in embodiments according to the invention;

Fig. 3 exemplifies the load behaviour of a heating system with water circulation according to the invention, with respect to time;

Fig. 4 shows an exemplary flow chart of the functional main steps of a control device according to the invention in controlling a heating system with water circulation; and

Fig. 5 exemplifies the functional elements of a load limiting device according to the invention.

The embodiments in the following description are presented as examples only, and a person skilled in the art may also carry out the basic idea of the invention in some other way than what is described in the description. Although the description may refer to a certain embodiment or embodiments in several contexts, this does not mean that the reference would be directed towards only one described embodiment or that the described feature would be usable in only one described embodiment. The individual characteristics of two or more embodiments may be combined and new embodiments of the invention may thus be provided.

Figures 1a and 1b have been described in connection with the description of the prior art.

Figure 2a shows an arrangement 20 according to a first embodiment of the invention for controlling the heating load of a building.

The load control arrangement of Fig.2a comprises a load limiting device 6 according to the invention, installed in parallel with a district heating control arrangement 10 of prior art as shown in Fig.1a. The load limiting device 6 is connected to the district heating meter 7 of the building by either a wired or a wireless communication link. Preferably, the load limiting device 6 is used for limiting at least one of the circulating water networks belonging to the heating water system 100A. Common circulating water systems include a radiator system and an underfloor heating system.

The load limiting device 6 is also electrically connected to a heating resistor 8 via a connection 6a. The load limiting device 6 controls the heating resistor 8 of the supply water sensor 3 of the heating system 100A according to a limiting level, for example so that the heating by the heating resistor 8 follows directly a limiting level of 0 to 100% determined by the load limiting device 6. When the limiting is at the maximum, the heating resistor is heated at maximum output. The output of the heating resistor 8 is determined according to the sensor used, and it is preferably in the order of 1 to 10 W.

In principle, the load limiting device 6 according to the invention does not adjust the heating of the building, but it only influences the temperature measurement data obtained by the temperature control device 1 of the building. Therefore, the load limiting device 6 according to the invention can be installed in parallel with any temperature control device 1 already existing in the building.

On the basis of the load measured by it, the load limiting device 6 determines the load limiting level which may be given, for example, as a percentage between 0 and 100%. The limiting is increased when the heating load measured by the load limiting device 6 exceeds a predetermined proactive upper limit, and correspondingly, the load limiting is reduced when the measured heating load drops below a predetermined proactive lower limit.

The district heating meter 7 transmits a meter pulse 7a reflecting the energy consumption of the building after a predetermined amount of thermal energy has been consumed. Preferably, the district heating meter may transmit a meter pulse 7a, for example, after the building has consumed, for example, 1 kWh or 10 kWh of thermal energy. Alternatively, the meter pulse 7a may also be generated on the basis of the amount of district heating water that has passed through the heat exchanger of the building. The amount of thermal energy needed for generating the meter pulse 7a is an amount of energy that can be determined according to the apparatus in question. Preferably, the amount of energy defined for the meter pulse 7a is such that the district heating meter 7 transmits several meter pulses 7a per hour in a cold heating season.

The load limiting device 6 according to the invention receives the meter pulse 7a transmitted by the district heating meter 7. After this, the load limiting device 6 computes the average load between the preceding meter pulse and the last received meter pulse, by dividing the amount of energy determined by the meter pulse by the time between the meter pulses.

At least one proactive upper limit is set in the load limiting device 6; if this limit is exceeded, the load limiting device 6 will switch on an electric current through the heating resistor 8 of the supply water sensor 3 of the heating system 100A. The heat generated by the heating resistor 8 heats 9 the supply water sensor 3 of the radiator network 100A.

In this way, the temperature measured by the supply water sensor 3 of the heating system 100A can be changed so that the temperature data 3a from the supply water sensor 3 to the temperature control device 1 of the building is higher than the real value. As a result, the temperature control device 1 will transmit a control command 1a to the valve 4 of the district heating network 10A, containing a new setting for the valve 4. The change in the setting of the valve will throttle the port of the valve 4. Thus, the change in the setting of the valve 4 will reduce the flow of hot water from the district heating network 10A by a rate which depends on the changed temperature value 3a of the supply water meter 3.

If the utilization of a communication bus is an option for data transmission in the district heating meter 7, various measurement data can be transferred from the district heating meter 7 to the load limiting device 6 according to the invention via the utilized communication bus, in real time if necessary, instead of the meter pulses 7a described above. Thus, the load limiting device may utilize the load data given by the district heating meter, wherein the load data does not have to be determined by the load limiting device on the basis of the meter pulses. Examples of communication buses of prior art, utilized in heating systems of buildings, include M-Bus and Modbus.

As a result of the reduced flow from the district heating network 10A, less thermal energy from the district heating network is needed in the building during the load limiting measures when the load limiting device 6 is used, compared with the control system of prior art (Fig.1) with no arrangement for limiting the peak load. Thus, by using the load limiting device 6 according to the invention, it is possible to prevent exceeding the load limit used as a basis for the basic fee for district heating, whereby savings are made in the basic fee costs.

Figure 2b shows an arrangement 20A for controlling the heating load in a heating system according to a second embodiment of the invention.

In the arrangement 20A for controlling the heating load in the heating system 100A shown in Fig.2b, the load limiting device 6 according to the invention is connected to at least one input of a temperature control device 1 in the building via a communication link 6c. In this embodiment, the load limiting device 6 according to the invention is configured to revise the target temperature value of the supply water sensor 3 of the heating system 100A preferably downwards by using the communication link 6c. Thus, the temperature control device 1 limits the flow of water from the district heating network 10A by transmitting a new setting in a control command 1a to the valve 4, to reduce the flow of hot water in the district heating network 10A.

In this embodiment, it is preferably not necessary to utilize a heating resistor 8 for heating the supply water sensor 3 in the heating system 100A.

Figure 2c shows an arrangement 20B for controlling the heating load according to a third preferred embodiment of the invention.

In this embodiment, an arrangement for controlling a hot water supply system 100B is also introduced in parallel with the arrangement 20A for controlling the heating system 100A shown in Fig.2a. Heat is supplied from a district heating network (reference 10B) via a heat exchanger to the hot water supply system 100B as well.

In the control arrangement 20B of Fig.2c, the thermal energy intake of the building from the district heating networks 10A and 10B is controlled, according to the invention, by means of corrected temperature data from both the supply water sensor 3 of the heating system 100A and the supply water sensor 33 of the hot supply water system 100B.

In this embodiment, it is also possible to change the temperature measured by the supply water sensor 33 of the hot supply water system 100B so that the temperature data 33a from the supply water sensor 33 of the hot supply water system 100B entered in the temperature control device 1 of the building is higher than the actual temperature. As a result, the temperature control device 1 will transmit a control command 1b to the valve 34 of the district heating network 10B, to change the setting of the valve 34. After receiving the control command 1b, the valve 34 will reduce the port of the valve 34 of the district heating network 10B to comply with the new setting. The change in the setting will reduce the flow rate of district heat from the district heating network 10B to the heat exchanger of hot supply water in the building, by a value depending on the value of the changed temperature 33a indicated by the supply water sensor 33.

In this embodiment, the load limiting device 6 according to the invention may heat either one or both of the heating resistors 8 or 38 of the district heating network 10A or the district heating network 10B, on the basis of the need for control computed in the load limiting device 6. If the load limiting device 6 heats both of the heating resistors 8 and 38, their heating capacities may be preferably unequal, for achieving an optimal load control in such a way that the users of the building will not suffer from temperature changes.

The arrangement shown in Fig.2c for controlling the supply water may also be utilized in the control arrangement of Fig.2b where no separate heating resistors 8 and 38 are used. In this preferred embodiment, the load limiting device 6 according to the invention is configured to revise the target temperature values of the supply water sensor 3 of the heating system 100A and the supply water sensor 33 of the hot supply water system 100B downwards, when the district heating load is limited. Thus, the temperature control device 1 will reduce the flow of water either in the district heating network 10A supplying the heating system 100A, or in the district heating network 10B supplying the supply water system 100B, or in both, by sending commands to the valves 4 and 34 to change the settings, in order to reduce the flow in at least one of the district heating networks.

Figure 2d shows how the heating resistor 8 or 38 in the control arrangement of the invention can be connected to a supply water sensor 3 or 33 in a water pipe 35 in a heating system 100A or a hot water supply system 100B. If the supply water sensor 3 or 33 is a surface sensor as shown in Fig.2d, the heating resistor 8 or 38 can be connected to the supply water sensor 3 or 33 by clamping, gluing or soldering. Preferably, highly heat conductive adhesive material is provided in the joint between the resistors 8 or 38 and the supply water sensor 3 or 33.

If the original supply water sensor 3 or 33 is of a type in which the sensor gauge is installed via a hole in the pipe 35 to the inside of the pipe 35, then the original supply water sensor can be replaced by a sensor that also comprises the heating resistor 8 or 38 according to the invention.

Figure 3 shows an example of how a load limiting device 6 according to the invention controls the intake of district heating in a building. In the example of Fig.3, the control measures taken by the load limiting device 6 according to the invention have succeeded in keeping the heating load curve 200 below the limit value 5 for the basic fee. When the load evens out below the limit value 5 for the basic fee, the load limiting device 6 according to the invention reduces the load limiting measures preferably gradually by reducing the electric current supplied to the heating resistors 8 and 38 connected to the supply water sensors 3 and 33.

In the upper part of Fig.3, a graph represents the district heating load of an exemplary building in kW as a function of time.

The lower part of Fig.3 shows the magnitude of limiting measures by a load limiting device 6 according to the invention as a function of time, in percentages of the maximum load limit at different times.

The exemplary limit value 5 (300 kW) for the basic fee in Fig.3 is the same as in the example of Fig.1b. In the example of Fig.3, one proactive upper limit 21 is programmed in the load limiting device 6 in the control arrangement according to the invention; exceeding this limit will trigger load limiting measures by the load limiting device 6 according to the invention. Reference 22 represents a proactive lower limit; a value lower than this will start a gradual reduction in the load limiting measures.

Preferably, more load limit values than are shown in Fig.3 may be utilized in the invention, between the proactive upper limit 21 and the proactive lower limit 22. Any exceeding of a load limit value between the above mentioned two limit values and closer to the proactive upper limit 21 than the previous exceeded load limit value, is preferably programmed to increase, for example, the electric current supplied to the heating resistors 8 and 38 shown in Fig.2c, the more, the closer the exceeded load limit value is to the proactive upper limit 21. In this way it is possible to set the temperature control device 1 of the building to limit the heating load more swiftly in a situation in which the heating load is either found or foreseen to increase rapidly, for whatever reason.

In a case where the load limiting device 6 according to the invention finds that the limit value 5 for the basic fee set for the building has been exceeded, the load limiting device 5 preferably triggers predetermined maximum load limiting measures defined for the load limiting device 6.

The example of Fig.3 shows a heating load curve 200 for an exemplary building as a function of time. At a moment of time 201, the heating load exceeds a proactive upper limit 21 according to the invention. As a result, the load limiting device 6 according to the invention triggers the load limiting measures. The load limiting device 6 is preferably programmed to increase the load limiting measures linearly from the moment of time 201, reference 200a.

The load limiting measures of the load limiting device 6 include, for example in the load limiting arrangement 20B of Fig.2c, applying the heating resistors 8 and/or 38 for heating at least one of the supply water sensors 3 or 33. As a result of the heating, the actual temperature control device 1 of the building receives a corrected temperature value 3a and/or 33a from the supply water sensor 3 and/or 33. Consequently, the temperature control device 1 transmits a new setting to the valve 4 in the district heating network 10A and/or to the valve 34 in the district heating network 10B, for limiting the flow rate of hot water from said district heating network. The limitation in the flow rate is preferably the greater, the faster or higher the load peak found or predicted by the load limiting device 6 according to the invention.

In the example of Fig.3, the load limiting device 6 according to the invention finds that the heating load of the resistor has been sufficient during the load limiting measures, whereby the load is lower than the proactive upper limit 21 at a moment of time 202. Thus, the load limiting measures are preferably kept constant at the achieved load limiting level; reference 200b.

In the example of Fig.3, however, the heating load of the building exceeds the proactive upper limit 21 according to the invention again at a moment of time 203. As a result, the load limiting device 6 according to the invention starts to increase the load limiting measures again from the moment of time 203, reference 200c. The load limiting device 6 is preferably programmed to increase the load limiting measures again linearly from the moment of time 203, reference 200c.

In the example of Fig.3, the load limiting device 6 according to the invention now finds that as a result of increasing the load limiting measures further, the load goes down below the proactive upper limit 21 again at a moment of time 204. Thus, the load limiting measures are preferably kept constant at the level achieved at the moment of time 204; reference 200d.

In the example of Fig.3, the load limiting device 6 finds next that the heating load drops below the proactive lower limit 22 for the load at a moment of time 205. Thus, the load limiting device 6 preferably decreases the load limiting. The phasing out of the load limiting is preferably programmed so that the load limiting device 6 reduces the load limiting measures linearly, reference 200e. However, after the moment of time 205, the reduction in the load limiting is preferably slower than the increase in the load limiting after the moment of time 201 described above.

In the example of Fig.3, the heating load of the building exceeds the proactive lower limit 22 according to the invention again at a moment of time 206. As a result, the load limiting device 6 according to the invention maintains the load limiting level achieved at the moment of time 206, from the moment of time 206; reference 200f.

In the example of Fig.3, the heating energy drops the proactive lower limit 22 again at a moment of time 207. Thus, the load limiting measures are gradually reduced again, preferably at the same rate of reduction, reference 200g, as after the moment of time 205.

In the example of Fig.3, the heating load of the building no longer exceeds the proactive lower limit 22. As a result, the limiting device 6 according to the invention stops the load limiting measures at a moment of time 208.

Operating in the district heating control arrangement 20A of Fig. 2b, for example, the load limiting device 6 according to the invention controls the temperature control device 1 of the building directly via a communication link 6c, for example by changing the target temperature of the supply water sensors 3 and/or 33 in such a way that the temperature control device 1 will transmit new settings to the valves 4 and/or 34, for reducing the flow rate of district heating water.

Figure 4 shows, as an exemplary flow chart, the main steps in the method according to the invention for limiting the district heating load, to be taken by the load limiting device 6 according to the invention. The method is utilized for preventing the shortterm heating peak load from exceeding a limit value (reference 5 in Fig.3) for the basic fee determined for the building.

In step 40, the load limiting device according to the invention, installed in parallel with the temperature control device 1 controlling the heating of the building, is activated. The activation may be either a one-off measure, whereby the load limiting device 6 is continuously active, or an activation in a given cold season.

At the beginning of step 41, the load limiting device 6 is on standby and is ready to receive a meter pulse 7a transmitted by the district heating meter 7 of the building, representing the thermal energy consumed. The district heating meter 7 transmits a meter pulse 7a whenever a predetermined amount of thermal energy has been consumed in the heating system of the building which preferably contains two circulating water systems: the heating system 100A and the hot water supply system 100B. The predetermined amount of energy for which the district heating meter 7 of the building transmits a meter pulse 7a may be preferably, for example, 1 kWh or 10 kWh. The amount of energy reflected by the meter pulse 7a is preferably determined according to the building to be such that several meter pulses 7a are transmitted per hour by the district heating meter 7 during a cold heating season. At the end of the step 41, the load limiting device 6 receives the meter pulse 7a transmitted by the district heating meter 7.

In step 42, the load limiting device 6 computes the thermal load of the building for the time between the latest received meter pulse 7a and the preceding meter pulse, by dividing the amount of energy indicated by the meter pulse 7a by the time elapsed between the receptions of the above mentioned meter pulses.

In step 43, the load limiting device 6 checks whether the first proactive upper limit 21 according to the invention, configured to trigger the measures according to the invention for limiting the heating load, has been exceeded. If the first proactive upper limit 21 for the heating load has not been exceeded, the control process returns to step 41, in which the load limiting device 6 is ready to receive the next meter pulse 7a from the district heating meter 7 of the building.

If it is found in step 43 that the proactive upper limit 21 for the heating load has been exceeded, the load control process according to the invention is started in step 44. Thus, the load limiting device 6 triggers the measures for limiting the district heating load. The limiting measures include correcting the temperature reading 3a or 33, measured by the supply water sensor 3 or 33 of at least one of the circulating water systems in the building, upwards. The correction in the temperature measurement may be made preferably by heating (references 9 and/or 39) the supply water sensor 3 or 33 by means of heating resistors 8 and/or 38.

In a preferred embodiment of the invention, the target temperature for the district heating temperature control device 1 of the building is corrected via one or more control inputs 6c in the temperature control device 1.

Step 45, in which the load limiting arrangement according to the invention is in operation, is similar to step 41. At the beginning of step 45, the load limiting device 6 is on standby and is ready to receive the next meter pulse 7a from the district heating meter 7 of the building. At the end of step 45, the load limiting device 6 receives a new meter pulse 7a from the district heating meter 7.

In step 46, the load limiting device 6 computes the average load of thermal energy for the time between the latest meter pulse 7a received during the load limiting measures, and the preceding meter pulse, by dividing the amount of energy of the meter pulse 7a by the time elapsed between said meter pulses.

The next steps 47a and 47b are comparative steps for finding out the current trend in the district heating load of the building.

In step 47a, the load limiting device 6 detects whether the load value is below the proactive upper limit 21 which is between the limit value 5 used for determining the basic fee for district heating, and the proactive lower limit 22.

If it is detected in step 47a that the load value is not below said proactive upper limit 21, the control process will return to step 44. Thus, at the beginning of the step, the electric current supplied to the heating resistors 8 and/or 38 of at least one supply water sensor 3 and/or 33 is increased, for raising the temperature measurement value 3a and/or 33a for supply water. After this, in step 44, the next meter pulse 7a is waited for.

If it is found in step 47a that the load value is below said proactive upper limit 21, the control process will proceed to the next comparative step 47b.

In the comparative step 47b, the measured value for the average load is compared, as in step 47a, to find out whether the measured average load has dropped below the proactive lower limit 22.

If it is found in step 47b that the load value has not dropped below said proactive lower limit 22 – the conclusion alternative "No" – the control process will move on to step 48 in which the load limiting measures are continued with the existing settings for the load limiting, and the load limiting process will return to step 44.

If it is found in step 47b that the load value has dropped below said second limit value – the conclusion alternative "Yes" – the control process will move on to step 49.

In step 49, the load limiting device 6 reduces the load limiting. After the conclusion has been made, the load limiting device 6 will reduce the load limiting, for example, by reducing the electric current supplied to the heating resistors 8 and/or 38 of the supply water meters 3 and/or 33. After this, the load limiting device 6 according to the invention will move on to step 44, to wait for the next meter pulse 7a.

After this, the four control loops 41 to 43; 44 to 47a; and 47a, 47b, 48, 44; or 47b, 49, 44 are repeated until the average district heating load of the building is reduced below the proactive upper limit 21, preferably permanently. When this situation is confirmed by the load limiting device 6, it ceases the load limiting measures. As a result, the intake of thermal energy in the building will be controlled by the temperature control device 1 for the heating load of the building.

All the adjustment process steps presented in Fig.4 may be implemented by computer program commands which are run in a suitable universal or special processor. The computer program commands may be stored on a computer readable medium, such as a data disc or a memory, from which the processor of the load limiting device 6 may retrieve said computer program commands for execution. The references to the computer readable media may also include, for example, special components, such as programmable USB flash memories, logic networks (FPLA), client-specific integrated circuits (ASIC), and signal processors (DSP).

Figure 5 shows a preferred embodiment, showing main functional components of the load limiting device 6 according to the invention.

The load limiting device 6 may preferably comprise an energy source 63, which may be a power supply connected to an alternating current network, an accumulator, or a battery. If the power source 63 is a battery, it is preferably chargeable. The electric components included in the load limiting device 6 are supplied with electric energy from this power source 63.

The load limiting device 6 comprises a central processor unit 61 (CPU) with a communication link to a memory 62. The memory 62 is used for storing the control algorithms/computer software and the limit values used for the control needed for running the load control process according to the invention. All the average load values computed by the load limiting device 6, and the data on the load limiting measures taken, with time stamps, are also stored in the memory 62, at least temporarily.

Preferably, three inputs are connected to the processor 61 of the load limiting device 6, via which inputs the load limiting device 6 has an effect on the measures taken by the actual temperature control device 1 of the building for controlling the use of district heating energy.

Via the input 65 limiting the heating, the load control device 6 supplies electric power to the heating resistor 8 coupled to the supply water sensor 3 of the heating system 100A when the load limiting device 6 has detected a need in limiting the load. The magnitude of electric power supplied to the heating resistor is determined by the load limiting device 6 on the basis of the need for limiting the load. The higher the heating power supplied to the heating resistor, the more swiftly and efficiently the temperature measurement value of the supply water sensor 3 is increased by the load limiting device 6. By increasing the temperature measurement value of the supply water sensor 3, the load limiting device 6 has an effect on the operation of the temperature control device 1 of the building. The electric power to be supplied to the heating resistor 8 can be preferably controlled by changing the supply voltage of the heating resistor 8. Alternatively, it is possible to apply time ratio control, whereby the supply voltage of the heating resistor 8 is a constant voltage but the constant supply voltage is broken on the basis of the need for control.

Via the input 66 for limiting the hot water supply, the load limiting device 6 preferably supplies electric power to the heating resistor 38 coupled to the supply water sensor 33 of the hot water supply system 100A as well, after the load limiting device 6 has found it necessary to apply load limiting in the supply water system 100B, too.

Via the control output 67, the load control device 6 controls the actual temperature control device 1 of the building, preferably directly. The control message to the temperature control device 1 may be, for example, a 0 to 10 V voltage message or a 4 to 20 mA current message, depending on the type of the temperature control device 1. By changing the voltage or the current, the load limiting device 1 according to the invention controls the operation of the actual temperature control device 1 of the building to restrict the energy intake from the district heating network by controlling the functional settings of the valves 4 and/or 34 in the district heating networks 10A and 10B.

Preferably, the load limiting device 6 may also comprise a user interface 68. The user interface preferably comprises a display unit and a suitable keypad for controlling the functions of the load limiting device 6. Preferably, the load limiting device 6 according to the invention may also comprise a wired or wireless data network connection 69 with suitable inputs and outputs for remote monitoring and remote control of the district heating load of the building.

Some preferred embodiments of the load limiting device, system arrangement, load limiting method, and computer program product to be utilized in the use of heating energy according to the invention have been described above. The invention is not limited to the solutions described above, but the inventive idea may be applied in a number of ways within the scope of the claims.

Claims

1. A method for limiting the heating load of a building, the method comprising – measuring the temperature with an outdoor thermometer (2),

– measuring the temperature of water supplied to at least one circulating water system (100A, 100b) of the building by a supply water sensor (3, 33),

– receiving the temperature measurement (2a) from the thermometer (2) and the temperature measurement (3a, 33a) from the supply water sensor (3, 33) by a temperature control device (1) of the building, and

– controlling at least one valve (4, 34) in the district heating network (10A, 10B) by the temperature control device (1) of the building on the basis of the outdoor temperature (2a) and the temperature measurement results (3, 3a) of the supply water sensor (3, 33), for maintaining the indoor temperature in the building;

characterized in that the method further applies a power limiting device (6) for – receiving (41) meter pulses (7a) reflecting the heating energy consumption, from the energy meter (7) of the building to the load limiting device (6);

– computing (42) the average heating load of the building between two successive meter pulses, by the load limiting device (6);

– comparing (43) the computed average heating load with a proactive upper limit (21) set for the heating load, by the load limiting device (6), and if the proactive upper limit (21) set for the heating load has been exceeded,

– triggering (44) measures for restricting at least one valve (4, 34) in the district heating network (10A, 10B), for reducing the heating load of the building by heating the supply water sensor (3, 33) of the at least one circulating water system (100A, 100B) by a heating resistor (8, 38).

2. The method according to claim 1 for limiting the heating load, characterized in that, when limiting the heating load, the method comprises

– receiving (45) meter pulses (7a) transmitted by an energy meter (7),

– computing (46) the average heating load of the building between each received meter pulse and the preceding meter pulse, by the load limiting device (6);

– comparing (47a) the computed average heating load with a proactive upper limit (21) set for the heating load, by the load limiting device (6), and if the load value is not below the proactive upper limit (21) for the heating load set, setting the measures for limiting the heating load constant by maintaining the electric power supplied to at least one heating resistor (8, 38) heating the supply water sensor (3, 33) of at least one circulating water system (100A, 100B).

3. The method according to claim 2 for limiting the heating load of a building, characterized in that, if the load value is below the proactive upper limit (21) set for the heating load, the method comprises

– comparing (47b) the computed average heating load with a proactive lower limit (22) also set for the heating load, by the load limiting device (6), and if the load value is below the proactive lower limit (22) set for the heating load,

– starting (49) measures for phasing out the limiting of the load of at least one district heating network (10A, 10B) by reducing the electric current supplied to at least one heating resistor (8, 38) heating the supply water sensor (3, 33) in the circulating water system (100A, 100B).

4. The method according to claim 3 for limiting the heating load of a building, characterized in that, if the load value is not below the proactive lower limit (22) for the heating load, the method comprises continuing the load limiting with the current load limiting settings.

5. The method according to claim 1 for limiting the heating load of a building, characterized in that the method comprises reducing the setting of the valve (4, 34) of at least one district heating network (10A, 10B) by transmitting correction data reducing the target temperature of the supply water sensor (3, 33), to the temperature control device (1) of the building.

6. The method according to claim 1 for limiting the heating load of a building, characterized by receiving, by the load limiting device (6), measuring data regarding the heating loading of the building from the energy meter (7) to the load limiting device (6) via a data communication bus.

7. The method according to any of the claims 1 to 6 for limiting the heating load, characterized in that the circulating water system, whose heating load is being limited, is either a heating system (100A) or a hot water supply system (100B).

8. An arrangement (10, 20, 20A, 20b) for limiting the heating load of a building, comprising

– an outdoor thermometer (2) for measuring the outdoor temperature,

– a supply water sensor (3, 33) for measuring the temperature of water supplied to at least one water supply system (100A, 100B),

– a temperature control device (1) of a building, the thermometer (2) and the supply water sensor (3, 33) being coupled to it; and

– the temperature control device (1) being configured to control the valve (4, 34) of at least one district heating network (10A, 10B) for controlling the temperature in the building, on the basis of the outdoor temperature and the temperature measurement data from the supply water sensor (3, 33), for maintaining the indoor temperature in the building;

characterized in that the arrangement for limiting the heating load further comprises a load limiting device (6) which is configured

– to receive (41) meter pulses (7a) reflecting the heating energy consumption, from the energy meter (7) of the building to the load limiting device (6);

– to compute (42) the average heating load of the building between two successive meter pulses, by the load limiting device (6);

– to compare (43) the computed average heating load with a proactive upper limit (21) set for the heating load, by the load limiting device (6), and if the proactive upper limit (21) set for the heating load has been exceeded,

– to trigger (44) measures for restricting at least one valve (4, 34) in the district heating network (10A, 10B), for reducing the heating load of the building, by heating the supply water sensor (3, 33) of the at least one circulating water system (100A, 100B) by a heating resistor (8, 38).

9. The arrangement (10, 20, 20A, 20B) according to claim 8 for limiting the heating load, characterized in that upon limiting the heating load, the arrangement for limiting the heating load is configured

– to receive (45) meter pulses (7a) transmitted by an energy meter (7),

– to compute (46) the average heating load consumed in the building between each received meter pulse and the preceding meter pulse, by the load limiting device (6); – to compare (47a), by the load limiting device (6), the computed average heating load with a proactive upper limit (21) set for the heating load, and if the load value is not below the proactive upper limit (21) for the heating load set, to set the measures for limiting the heating load constant by maintaining the electric power supplied to at least one electric resistor (8, 38) heating the supply water sensor (3, 33) in at least one circulating water system (100A, 100B).

10. The arrangement according to claim 9 for limiting the heating load, characterized in that if the load value is below the proactive upper limit (21) for the heating load, the arrangement is further configured

– to compare (43) the computed average heating load with a proactive lower limit (22) set for the heating load, by the load limiting device (6), and if the load value is below the proactive lower limit (22) set for the heating load,

– to start (49) measures for phasing out the limiting of the load of at least one district heating network (10A, 10B) by reducing the electric current supplied to at least one electric resistor (8, 38) heating the supply water sensor (3, 33) in the circulating water system (100A, 100B).

11. The arrangement according to claim 8 for limiting the heating load of a building, characterized by receiving, by the load limiting device (6), measuring data regarding the heating loading of the building from the energy meter (7) to the load limiting device (6) via a data communication bus.

12. The arrangement according to claim 8, 9, 10, or 11 for limiting the heating load, characterized in that the water supply system, whose intake of thermal energy is being limited, is either a heating system (100A) or a hot water supply system (100B).

13. A load limiting device (6) for limiting the district heating load of a building, characterized in that the load limiting device (6) comprises means

– for receiving (41) meter pulses (7a) reflecting the heating energy consumption, coming from the energy meter (7) of the building to the load limiting device (6),

– for computing (42) the average heating load of the building between two successive meter pulses,

– for comparing (43) the computed average heating load with a proactive upper limit (21) set for the heating load, and if the proactive upper limit (21) set for the heating load has been exceeded,

– for triggering (44) measures for restricting at least one valve (4, 34) in the district heating network (10A, 10B), for reducing the heating load of the building, by heating the supply water sensor (3, 33) of the at least one circulating water system (100A, 100B) by a heating resistor (8, 38).

14. The load limiting device according to claim 13, characterized in that the load limiting device further comprises, for limiting the heating load, means

– for comparing (47a) the computed average heating load with a proactive upper limit (21) set for the heating load, and if the load value is not below the proactive upper limit (21) set for the heating load,

– for setting the measures for limiting the heating load constant, by maintaining the electric power constant in the heating resistor (8, 38) heating the supply water sensor (3, 33) of at least one circulating water system (100A, 100B).

15. The load limiting device according to claim 14, characterized in that if the load value is below the proactive upper limit (21) for the heating load, the device further comprises means configured

– to compare (43) the computed average heating load with a proactive lower limit (22) set for the heating load, and if the load value is below the proactive lower limit (22) set for the heating load,

– to start (49) measures for phasing out the limiting of the load of at least one district heating network (10A, 10B) by reducing the electric current supplied to the heating resistor (8, 38) heating the supply water sensor (3, 33) of at least one circulating water system (100A, 100B).

16. The load limiting device according to claim 13, characterized by receiving, by the load limiting device (6), measuring data regarding the heating loading of the building from the energy meter (7) to the load limiting device (6) via a data communication bus.

17. The load limiting device according to claim 13, characterized in that it comprises means for reducing the setting of the valve (4, 34) of at least one district heating network (10A, 10B) by transmitting (6b) data correcting the target temperature of the supply water sensor (3, 33) of at least one circulating water system, to the temperature control device (1) controlling the heating load of the building.

18. A computer program product, characterized in that it comprises computer program code means stored on a computer readable storage medium, the code means being configured to execute all the steps of the load limiting method defined in one of claims 1 to 6 when said computer program is run in a processor of a data processing device.