US20130168459A1

US20130168459A1 - Low-Power Residential Heating System

Info

Publication number: US20130168459A1
Application number: US13/822,222
Authority: US
Inventors: Cedric Paulus; Florent Lefrancois
Original assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2010-09-14
Filing date: 2011-09-12
Publication date: 2013-07-04
Also published as: AU2011304009B2; AU2011304009A1; BR112013005611A2; FR2964727A1; ZA201301857B; EP2616744B1; CN103154619A; WO2012034965A1; JP2013542390A; FR2964727B1; EP2616744A1

Abstract

Method of thermal management of a building, on the basis of a thermal system equipped with a low-power generator, characterized in that it comprises a step (E3) of turning on the generator ahead of time in the absence of any occupant in the building so as to comply with a future comfort setpoint at a future instant (H), by taking account of the energy available (E_generator _— _H) at the generator up until this future instant (H) and of the energy necessary (E_heating _— _H) to reach the future comfort setpoint within the building at this future instant (H).

Description

The invention relates to a method of thermal management of a building as well as to a thermal system implementing such a method. It also pertains to a medium comprising software implementing such a method. Finally, it also relates to a building equipped with such a thermal system.
During phases of unoccupancy of buildings, their temperature is often reduced so as to save energy. Accordingly, the heating is for example turned off for a certain period, until an interior temperature corresponding to a low setpoint temperature is reached. Afterwards, when the occupants return, the maximum comfort temperature is again sought. A so-called restart phase is launched, which consists in heating the building again so as to switch back from the low interior temperature to the high interior temperature.
A first solution of the prior art relies on an energy generator operating according to a mode of regulation of the temperature between two temperature setpoints, high and low, the high setpoint temperature being used at times when the occupants are present whereas the low setpoint temperature is used when they are absent. This solution allows an energy saving with respect to a solution in which the maximum comfort temperature were always sought but remains very simplistic and non-optimized. Moreover, the low setpoint temperature is often specified in a random manner by the occupants themselves, or predefined in the factory without taking account of the actual climate. Thus, when the occupants return, it may happen that the heating time to reach the comfort temperature is very long, if the temperature has been overly reduced. In such a case, the restart phase seems interminable. Conversely, it may happen that the low setpoint temperature has been chosen too high and has caused needless energy consumption in the absence of its occupants. Moreover, an occupant will have a tendency to specify setpoint temperatures that do not correspond to his real timetable in order to attempt to anticipate a possible failure, or if he has heard weather forecasts for low temperature. Thus, it is clearly apparent that the optimization of such a system is very difficult. In practice, this results in dissatisfaction of the occupants who do not always have their comfort temperature within acceptable timescales and high and non-optimized energy consumption.
A second solution of the prior art relies on heating systems taking the form of multifunction apparatuses which in fact integrate two complementary generators: a basic generator of low power, for example between 1.5 to 6 kW, used for the energy needs under steady-state circumstances and particularly suited to heavily insulated, so-called low energy consumption, buildings which are under full development, and a booster generator of high power, of possibly as much as four times the basic power, for example between 6 and 9 kW, used for short transient circumstances. This second solution still operates according to temperature regulation on the basis of a comfort temperature and a low temperature for the unoccupancy phases. By virtue of the high-power generator, used exclusively for the restart phases, the comfort temperature is in general reached within a satisfactory time. This solution exhibits the first drawback of demanding a high investment cost to equip a building. It exhibits moreover a second drawback of giving rise to periods of high peaks of energy consumption, thereby complicating the overall energy management of a district, while demanding subscriptions from each individual to an electrical network suited to their occasional needs for high power, this generally exhibiting a significant cost for short periods of use. Finally, it still exhibits the same drawback of fine tuning as the first solution of the prior art, in particular in respect of the choice of the value of the absence setpoint temperature.
Thus, a general object of the invention is to propose an improved solution for the thermal management of a building, which solves all or some of the previous drawbacks.
For this purpose, the invention relies on a method of thermal management of a building, on the basis of a thermal system equipped with a low-power generator, characterized in that it comprises a step (E3) of turning on the generator ahead of time in the absence of any occupant in the building so as to comply with a future comfort setpoint at a future instant (H), by taking account of the energy available (E_generator _— _H) at the generator up until this future instant (H) and of the energy necessary (E_heating _— _H) to reach the future comfort setpoint within the building at this future instant (H).
The future comfort setpoint can be a temperature setpoint and the method can comprise the following steps:

- (E1)—Calculation of the energy available (E_generator _— _H) at the generator up until the future instant (H);
- (E2)—Calculation of the energy necessary (E_heating _— _H) to reach the setpoint temperature within the building at this instant (H);
- (E3′)—Comparison of the above two values and turning on of the generator if E_generator _— _H<E_heating _— _H.

The future comfort setpoint can be a maximum duration (tmax) permitted so as to reach a comfort temperature in case of necessity at the future instant (H).
The method can comprise the following steps:

- (E1)—Calculation of the energy available (E_generator _— _H) at the generator up until the future instant (H);
- (E2)—Calculation of the energy necessary (E_heating _— _H) to reach the setpoint temperature within the building at this instant (H);
- (E3″)—Comparison of the above two values and turning on of the generator if H>tmax.

The method of thermal management of a building can comprise a step of calculating a low setpoint temperature so as to regulate the operation of the generator in the absence of any occupant in the building, this low setpoint being variable over time.
The method of thermal management of a building can comprise a step of inputting at least one of the following data:

- Inputting of at least one temperature setpoint in the case of occupancy of the building and/or in the case of non-occupancy; and/or
- Inputting of the periods of occupancy and/or of non-occupancy of the building; and/or
- Inputting of a permitted maximum duration (tmax) of operation of the generator so as to reach a certain comfort temperature in the building.

The method can comprise a step of evaluating the future exterior temperature over several instants (H) of a future period (P).
The method can comprise a step of auto-learning of the thermal characteristics of the building.
The method of thermal management of a building can comprise the calculation of the energy available (E_generator _— _H) at the generator up until the future instant (H) through the following equation:
$E_{generator_H} = \sum_{1}^{H} P_{nominal}$
where P_nominalis the nominal power of the generator, or through the following equation:
$E_{generator_H} = \sum_{1}^{H} (a \times T_{e_evap} + b \times T_{e_evap}^{2} + c \times T_{e_cond} + d)$

With:

a, b, c, d: characteristic parameters of a heat pump;
T_e _— _evap: input temperature at the evaporator of the heat pump;
T_e _— _cond: input temperature at the condenser of the heat pump.
The method of thermal management of a building can comprise the calculation of the energy necessary (E_heating _— _H) to reach an interior setpoint temperature of the building at the instant (H) through the following equation:
$E_{heating_H} = ({CAP}_{st} + {CAP}_{it}) \times (T_{int_setp_H} - T_{int}) + GV \times \sum_{1}^{H} [(T_{int} + (T_{int_setp_H} - T_{int}) / 2) - T_{ext_H}]$

With:

T_int: interior temperature at the present instant;
T_int _— _setp _— _H: interior setpoint temperature at the instant H;
T_ext _— _H: estimated exterior temperature at the instant H;
CAP_st: short-term heat capacity of the building;
CAP_lt: long-term heat capacity of the building;
GV: heat waste coefficient for the building.
The method of thermal management of a building can comprise the repetition for several instants (H) of a future period (P) of a step of estimating the need to turn on the generator ahead of time in the absence of any occupant in the building so as to comply with a future comfort setpoint at a future instant (H), by taking account of the energy available (E_generator _— _H) at the generator up until this future instant (H) and of the energy necessary (E_heating _— _H) to reach the future comfort setpoint within the building at this future instant (H).
The invention also pertains to a computer medium comprising a computer program implementing the steps of the method of thermal management of a building such as described above.
The invention also pertains to a system for thermal management of a building comprising a low-power generator, characterized in that it comprises a control unit which implements the method of thermal management of a building such as described above.
The control unit can comprise a first module for estimating the exterior temperature over a future period, a second module for estimating the energy available in the generator for the period considered, a third module for learning the thermal characteristics of the building so as to model its thermal behaviour, a fourth module for determining the energy necessary for the building and a fifth module for thermal driving of the generator.
The invention also pertains to a building characterized in that it comprises a thermal management system implementing the thermal management method such as described above.

These objects, characteristics and advantages of the present invention will be set forth in detail in the following description of a particular mode of execution given without limitation in conjunction with the attached figures among which:

FIG. 1 schematically illustrates a thermal system for a building according to a mode of execution of the invention.

FIG. 2 represents the comparative evolution of interior temperatures of a building with or without the mode of execution of the invention according to a first scenario.

FIGS. 3 and 4 represent the comparative evolution of interior temperatures of a building with or without the mode of execution of the invention according to a second scenario.

The mode of execution of the invention defines a thermal system for managing the energy of a building, within the framework of the heating of a building. However, the concept of the invention remains applicable to any thermal management of the building, for its air-conditioning, its ventilation, etc.
The thermal system according to the mode of execution of the invention takes the form of a heating system, comprising a single generator of low power and a control unit, comprising one or more hardware means and/or software means, including a microprocessor for example, implementing the thermal management method which will be described subsequently.
The thermal system according to the mode of execution of the invention takes the form of an apparatus comprising a heat pump and exhibiting the various modules represented schematically in FIG. 1. The first module 10 implements a function for estimating the exterior temperature over a future period P. The second module 20 implements a function for estimating the energy available in the generator for the period P considered. The third module 30 implements a function for learning the thermal characteristics of the building so as to model its thermal behaviour. The fourth module 40 implements a function for determining the energy necessary for the heating of the building over the period P. Finally, the fifth module 50 fulfils the function for thermal management of the building, for driving the heating. Finally, the thermal system comprises a man machine interface, not represented, which allows a resident to input his occupancy periods, and/or a setpoint comfort temperature, and/or a value of maximum heating time, which will be explained subsequently.
The concept of the invention consists in eliminating the power peaks for the heating restart phases, for example when the occupants enter an unoccupied building, by anticipating their entry by heating the building on the basis of a low power, at least partially before their entry, in a manner calculated for energy optimization. Accordingly, the thermal system studies in advance the thermal situation over a future period P within the building.
This concept will now be detailed by describing more precisely the various modules of the thermal system according to the mode of execution of the invention. By way of example, the thermal system will anticipate the situation according to an hourly period, that is to say hour by hour, and for a period P corresponding to the next 24 hours: as a variant, the same principle will be able to be implemented for any future period other than 24 hours and for any time interval other than an hour.
The function of the first module 10 of the invention is therefore to estimate the exterior temperature outside the building for each hour of the next 24 hours. Accordingly, any existing procedure can be implemented, such as that described in document EP2146309, the invention not pertaining to this module specifically.
By way of example, the exterior temperature can be obtained through a first estimation of the average exterior temperature T_ext _— _avg _— _Pover the next 24 hours, as a function of the maximum exterior temperature T_ext _— _max _— _P-1and/or minimum exterior temperature T_ext _— _min _— _P-1measured for the previous period of 24 hours, and/or of the exterior temperature measured at the present instant. Accordingly, the thermal system is equipped with an exterior thermometer allowing it to ascertain at any instant the measured exterior temperature T_ext.
The average exterior temperature over the next 24 hours may depend on the hour of the calculation and be defined by the following formulae:
At 6 H: T _ext _— _avg _— _P=(T _ext _— _measured _— _6H +T _ext _— _max _— _P-1)/2
At 10 H: T _ext _— _avg _— _P =T _ext _— _measured _— _10H
At 15 H: T _ext _— _avg _— _P=(T _ext _— _min _— _P-1 +T _ext _— _measured _— _15H)/2
At 22 H: T _ext _— _avg _— _P =T _ext _— _measured _— _22H
Thereafter, on the basis of the estimated average exterior temperature for the period P, the time profile of the exterior temperature for this period P is estimated by the following sine function:
T _ext _— _H _— _P=[(T _ext _— _min _— _P +T _ext _— _max _— _P)/2]+[(T _ext _— _min _— _P −T _ext _— _max _— _P)/2]*sin [((H+n)−9)π/12]

With:

T_ext _— _H _— _P: estimated exterior temperature at the hour H of the period P,
T_ext _— _min _— _P: minimum exterior temperature of the next 24 hours,
T_ext _— _max _— _Pmaximum exterior temperature of the next 24 hours,
n: actual hour of the day.
To apply this function, the module 10 therefore estimates beforehand the values of minimum T_ext _— _min _— _Pand maximum T_ext _— _max _— _Paverage exterior temperature for the next 24 hours.
Accordingly, the following formulae can be used:
At 6H: T _ext _— _min _— _P =T _ext _— _measured _— _6Hand T _ext _— _max _— _P=2*T _ext _— _avg _— _P −T _ext _— _measured _— _6H
At 10H: T _ext _— _min _— _P =T _ext _— _min _— _p-1and T _ext _— _max _— _P=2*T _ext _— _avg _— _P −T _ext _— _min _— _P-1
At 15H: T _ext _— _min _— _P =T _ext _— _min _— _P-1and T _ext _— _max _— _P =T _ext _— _measured _— _15H
At 22H: T _ext _— _min _— _P=2*T _ext _— _avg _— _P −T _ext _— _max _— _P-1and T _ext _— _max _— _P =T _ext _— _max _— _P-1
Following the above description, it is therefore apparent that the first module 10 needs a single datum as input, the past and present exterior temperature. The latter can be measured or estimated.
As a variant, the above calculation could integrate or be replaced with forecast data, transmitted for example by a meteorological remote server.
The second module 20 implements a function for estimating the energy available in the generator for the period P considered. Accordingly, the simplest calculation consists in considering the nominal power P_nominal(in kJ/h) of the generator so as to deduce therefrom the energy available through the following formula:
$E_{generator_H} = \sum_{1}^{H} P_{nominal}$

With:

E_generator _— _H: energy available (in kJ) at the generator up until the hour H;
H: the hour from among the next 24 hours for which the energy available at the generator is estimated.
Naturally, this calculation is suited to the type of generator used. The above formula is very suited to heating based on electrical resistance. However, if the generator is an extracted air/fresh air heat pump, the energy available can be calculated through the following equation:
$E_{generator_H} = \sum_{1}^{H} (a \times T_{e_evap} + b \times T_{e_evap}^{2} + c \times T_{e_cond} + d)$

With:

a, b, c, d: parameters characteristic of the heat pump;
T_e _— _evap: input temperature at the evaporator of the heat pump;
T_e _— _cond: input temperature at the condenser of the heat pump;
H: the hour from among the next 24 hours for which the energy available at the generator is estimated.
In the case of an air/air heat pump, such as illustrated in FIG. 1, it is possible to consider the following relations:
T _e _— _evap =T _int
T _e _— _cond =T _ext _— _H
Naturally, the second module 20 does not pertain specifically to the above equations and any model for calculating the energy available at a certain hour H in the course of a next period P can be implemented. In this case, the input data of the module will be suited to this other calculation model.
The third module 30 implements a function for learning the thermal characteristics of the building so as to model its thermal behaviour.
Accordingly, the mode of execution of the invention considers the thermal model represented by the following equation:
$E_{heating_H} = ({CAP}_{st} + {CAP}_{it}) \times (T_{int_setp_H} - T_{int}) + GV \times \sum_{1}^{H} [(T_{int} + (T_{int_setp_H} - T_{int}) / 2) - T_{ext_H}]$

With:

E_heating _— _H: heating energy necessary up until the hour H (in kJ);
T_int: interior temperature at the present instant (in K);
T_int _— _setp _— _H: interior setpoint temperature at the hour H (in K);
T_ext-H: estimated exterior temperature at the hour H;
CAP_st: short-term heat capacity of the building (in fact representing the furniture mainly) (in kJ/K);
CAP_lt: long-term heat capacity of the building (in fact representing the walls mainly) (in kJ/K);
GV: heat waste coefficient for the building (in kJ/(h·K));
H: the hour from among the next 24 hours for which the energy available at the generator is estimated.
This equation can be written in a matrix manner as:
E _heating _— _H=θ^Tφ
where θ^Tis the transpose of the matrix θ.
With θ=[CAP_stCAP_ltGV]
φ=[(T _int _— _setp _— _H −T _int)(T _int _— _setp _— _H −T _int)Σ₁ ^H[(T _int+(T _int _— _setp _— _H −T _int)/2)−T _ext _— _H]]
This module 30 implements an auto-adaptation of the thermal parameters of the building as a function of the knowledge of the actual restart phases. Accordingly, for each restart phase it compares the energy actually expended by the generator with that predicted by the model hereinabove and adjusts the thermal parameters if these two values differ.
The actual heating energy can either be directly measured by an energy meter situated on the heating circuit for example, or be estimated as a function of the operating time of the generator and an energy consumption model such as those set forth within the framework of the description of the second module 20.
The auto-adaptation of the thermal parameters CAP_st, CAP_lt, and GV, can be based on the following algorithm:
θ(j)=θ(j−1)+K(j)·e(j)
where j represents the day considered.
The matrices e and K represent respectively the a priori error between the measured heating need and the estimated heating need, and the adaptation gain to be applied to take account of this error. These two matrices are calculated in the following manner:
The a priori error: e(j)=E _heating(j)−φ^T(j)θ(j−1)
Adaptation gain: K(j)=(P(j−1)φ(j))/(λ/μ+θ^T(j)P(j−1)θ(j))
The matrix P is updated in the following manner:
P(j)=1/λ[P(j−1)−P(j−1)φ(j)φ^T(j)P(j)/[(λ/μ+θ^T(j)P(j−1)θ(j))]]
Where the coefficient λ is a forget factor and the coefficient μ a weighting factor.
Naturally, this module could allow auto-adaptation of any thermal model of the abode, is not limited to that described hereinabove. Moreover, this auto-adaptation could be fine-tuned according to various procedures.
The fourth module 40 implements a function for determining the energy necessary for the heating of the building over the period P.
It therefore comprises as input the following parameters:

- The thermal model defined by the third module described hereinabove;
- An estimation of the exterior temperature for the period P, provided by the first module;
- An interior setpoint temperature profile.

It implements the thermal model of the building, fine-tuned by the module described above, to obtain the energy necessary to reach the setpoint temperature at an hour H of the period P through the formula:
$E_{heating_H} = ({CAP}_{st} + {CAP}_{it}) \times (T_{int_setp_H} - T_{int}) + GV \times \sum_{1}^{H} [(T_{int} + (T_{int_setp_H} - T_{int}) / 2) - T_{ext_H}]$
The fifth module 50 fulfils the function for thermal management of the building, for driving the heating system.
In particular, it compares the results of the second and fourth modules 20, 40 with the aim of turning on the generator ahead of time in an appropriate manner to obtain the setpoint temperature at any hour H, while using reduced heating power. This turning on ahead of time is particularly relevant for managing the changes of occupancy of the building, corresponding to the restart phases explained above.
The thermal system described hereinabove exhibits the advantage of high autonomy since it allows its implementation in any unknown environment.
Its auto-learning and its design allow it to determine in an autonomous manner and to acquire all the parameters necessary for its optimal operation. Thus, it will advantageously take the form of a single apparatus, grouping together in one and the same casing all the modules described hereinabove and the generator as such. Optionally, a man machine interface can make it possible to manually modify certain parameters if necessary, such as the setpoint temperatures.
During its first turning on, it comprises initialization parameters which can be average values, specified in the factory, without the need for high accuracy.
As a variant however, the thermal system of the invention might not comprise the modules 10 and 30, these functions being able to be outsourced to any other system, communicating with the thermal system so as to transmit the significant parameters to it. Thus, as we have seen, the future exterior temperature could be transmitted by a meteorological base, and the intrinsic thermal parameters of the building could be specified by the constructor of the building, or calculated by any other independent device.
Thus, the thermal system of the invention implements the method for managing the thermal energy of the abode comprising the following steps E1, E2, E3′:

- E1—Calculation of the energy available E_generator _— _H(in kJ) at the generator up until a future hour H;
- E2—Calculation of the necessary energy E_heating _— _Hto reach the setpoint temperature within the building at this hour H;
- E3′—Comparison of the above two values and turning on of the generator as soon as E_generator _— _H<E_heating _— _H.

This method thus makes it possible to guarantee that the time remaining up until the hour H is sufficient for the generator to reach the setpoint temperature at the desired hour H by operating in a normal circumstance, without demanding a particular power.
As a remark, the invention therefore makes it possible to turn on the generator ahead of time so as to best follow the temperature setpoints sought while operating with a normal operation, without high-power mode to manage the restart phases. As a remark, this turning on ahead of time can stray slightly from the rule fixed in step E3′ hereinabove without departing from the concept of the invention.
Thus, step E3′ can more generally consist in turning on the generator ahead of time so as to comply with a future temperature setpoint, by taking account of the energy available E_generator _— _H(in kJ) at the generator up until a future hour H and of the energy necessary E_heating _— _Hto reach the setpoint temperature within the building at this hour H.
The above method operates well for managing programmed restarts, on the basis of setpoint temperatures defined in advance. However, certain unforeseen situations may arise in which a resident returns to his residence earlier than envisaged, or at an indeterminate instant. In such a case, he has no means of speeding up the heating of his residence since this heating depends solely on the limited power of his single generator.
To cater for a minimum of comfort to cope with these situations, the thermal system contrives matters so that at any instant, the time necessary to reach a comfort setpoint temperature corresponding to the occupancy of the building, is not greater than a predefined threshold tmax, thereby guaranteeing this resident that the comfort temperature will be obtained in a reasonable predetermined time.
Accordingly, the method for the thermal management of the abode comprises a step which consists in verifying that in the case of immediate turning on of the generator, the time necessary to reach the comfort setpoint temperature does not exceed the threshold tmax.
Thus, even if step E3′ verifies that E_generator _— _H>E_heating _— _H, if H>tmax then the generator is turned on, according to a step E3′.
Thus ultimately, the concept of the invention relies on a step E3 of turning on the generator ahead of time so as to comply with a comfort setpoint, be it a temperature or a duration of heating, by taking account of the energy available E_generator _— _H(in kJ) at the generator up until a future hour H and of the energy necessary E_heating _— _Hto reach the setpoint within the building at this hour H.
As a remark, with such an approach, the occupant no longer needs to indicate a low temperature setpoint to the thermal system: just the maximum time tmax defined hereinabove suffices to manage the thermal environment of the abode in its unoccupancy periods. This is markedly more user-friendly, economical and satisfactory. However, it can moreover also operate with a low setpoint temperature, for example a no-freeze temperature below which the system must not descend.
The method for the thermal management of the abode comprises a prior step of inputting all or some of the following data, by an occupant or a builder:

- Inputting of at least one comfort temperature in the case of occupancy of the building;
- Inputting of the periods of occupancy and/or of absence from the building;
- Inputting of a permitted maximum duration tmax of heating of the building.

The steps of the above-described method will preferably be implemented for any future hour H of the future period P considered. They will be particularly relevant for the hours H for which the building switches from an unoccupied to an occupied state, that is to say the management of the restart phases.
Moreover, the invention has been illustrated to cater for the heating of a building but it is naturally apparent that it could easily be implemented to manage its air-conditioning.
Thus, the solution adopted caters well for the objects of the invention and exhibits the following advantages:

- it limits the power peaks by avoiding recourse to a high-power complementary generator;
- It satisfies the thermal comfort of the residents while saving costs;
- It makes it possible to use low-power generators, which are sufficient for well insulated buildings.

FIGS. 2 to 4 illustrate by way of example the operation of the solution described in comparison with the two prior art solutions presented in the preamble.
The first solution of the prior art relies on a 2-kW generator operating between two setpoint temperatures T1 and T2, for example 16 and 19° C. At the instant t1, which must correspond to the occupancy hour of the building, the temperature setpoint switches from T1 to T2. The generator turns on at this instant t1 and reaches the setpoint temperature T2 along the slope 11.
The second solution of the prior art relies on a 2-kW basic generator and a 6 kW complementary generator. At the instant t1, it reaches the setpoint value along the slope 12, much more rapidly since the high-power generator is used for this restart phase.
The thermal system according to the invention in fact determines the instant t0 preceding the instant t1, for which it is necessary to turn on the generator, to reach the setpoint temperature T2 at the instant t1, according to a slope 13 parallel to that of the first solution. By virtue of this solution, the user's comfort is satisfied, without resorting to high heating powers.
FIG. 3 represents the behaviour of the two solutions of the prior art in a scenario of lengthy absence. Such a scenario is distinguished from the previous in that it is possible to allow the interior temperature to descend lower in order to make greater savings. However, this complicates the restart phase.
During the absence, the regulation is done around the low setpoint temperature T1 at 12° C. At the instant t1, the occupant returns home and raises the temperature setpoint to the value T2 of 19° C. The first solution reaches the high setpoint along the slope 21, in about 12H, slower than the slope 22 of the second solution, which reaches the setpoint in 4H, despite its high power which is no longer satisfactory in such a scenario. As a remark, the curve 27 illustrates the exterior temperature variation during this period.
FIG. 4 illustrates the same scenario with the thermal system of the invention. During the absence period, the interior temperature 24 is not regulated around the low setpoint T1 but around a setpoint represented by the curve 25, calculated automatically by the system, which thus varies over time, since it depends in particular on the exterior temperature, and is about 2° C. above T1. Thus, at the instant t1, only a reduced time is required in order for the slope 23 to reach the setpoint, in about 6H. In this solution, the thermal system has therefore automatically determined the heating necessary during the absence to reach these 6H of heating upon return, without knowing the instant of this return, thereby making it possible to cater for the occupant's desire for comfort, at minimum cost.

Claims

1. Method of thermal management of a building, on the basis of a thermal system equipped with a low-power generator, wherein it comprises a step (E3) of turning on the generator ahead of time in the absence of any occupant in the building so as to comply with a future comfort setpoint at a future instant (H), by taking account of the energy available (E_generator _— _H) at the generator up until this future instant (H) and of the energy necessary (E_heating _— _H) to reach the future comfort setpoint within the building at this future instant (H).

2. Method of thermal management of a building according to claim 1, wherein the future comfort setpoint is a temperature setpoint and in that it comprises the following steps:

(E1)—Calculation of the energy available (E_generator _— _H) at the generator up until the future instant (H);

(E2)—Calculation of the energy necessary (E_heating _— _H) to reach the setpoint temperature within the building at this instant (H);

(E3′)—Comparison of the above two values and turning on of the generator if E_generator _— _H<E_heating _— _H.

3. Method of thermal management of a building according to claim 1, wherein the future comfort setpoint is a maximum duration (tmax) permitted so as to reach a comfort temperature in case of necessity at the future instant (H).

4. Method of thermal management of a building according to claim 3, wherein it comprises the following steps:

(E3″)—Comparison of the above two values and turning on of the generator if H>tmax.

5. Method of thermal management of a building according to claim 4, wherein it comprises a step of calculating a low setpoint temperature to regulate the operation of the generator in the absence of any occupant in the building, this low setpoint being variable over time.

6. Method of thermal management of a building according to claim 1, wherein it comprises a step of inputting at least one of the following data:

Inputting of at least one temperature setpoint in the case of occupancy of the building and/or in the case of non-occupancy; and/or

Inputting of the periods of occupancy and/or of non-occupancy of the building; and/or

Inputting of a permitted maximum duration (tmax) of operation of the generator so as to reach a certain comfort temperature in the building.

7. Method of thermal management of a building according to claim 1, wherein it comprises a step of evaluating the future exterior temperature over several instants (H) of a future period (P).

8. Method of thermal management of a building according to claim 1, wherein it comprises a step of auto-learning of the thermal characteristics of the building.

9. Method of thermal management of a building according to claim 1, wherein it comprises the calculation of the energy available (E_generator _— _H) at the generator up until the future instant (H) through the following equation:

E_{generator_H} = \sum_{1}^{H} P_{nominal}

where P_nominalis the nominal power of the generator,

or through the following equation:

E_{generator_H} = \sum_{1}^{H} (a \times T_{e_evap} + b \times T_{e_evap}^{2} + c \times T_{e_cond} + d)

With:

a, b, c, d: characteristic parameters of a heat pump;

T_e _— _evap: input temperature at the evaporator of the heat pump;

T_e _— _cond: input temperature at the condenser of the heat pump.

10. Method of thermal management of a building according to claim 1, wherein it comprises the calculation of the energy necessary (E_heating _— _H) to reach an interior setpoint temperature of the building at the instant (H) through the following equation:

E_{heating_H} = ({CAP}_{st} + {CAP}_{it}) \times (T_{int_setp_H} - T_{int}) + GV \times \sum_{1}^{H} [(T_{int} + (T_{int_setp_H} - T_{int}) / 2) - T_{ext_H}]

With:

T_int: interior temperature at the present instant;

T_int _— _setp _— _H: interior setpoint temperature at the instant H;

T_ext _— _H: estimated exterior temperature at the instant H;

CAP_st: short-term heat capacity of the building;

CAP_lt: long-term heat capacity of the building;

GV: heat waste coefficient for the building.

11. Method of thermal management of a building according to claim 1, wherein it comprises the repetition for several instants (H) of a future period (P) of a step of estimating the need to turn on the generator ahead of time in the absence of any occupant in the building so as to comply with a future comfort setpoint at a future instant (H), by taking account of the energy available (E_generator _— _H) at the generator up until this future instant (H) and of the energy necessary (E_heating _— _H) to reach the future comfort setpoint within the building at this future instant (H).

12. Computer medium comprising a computer program implementing the steps of the method of thermal management of a building according to claim 1.

13. System for thermal management of a building comprising a low-power generator, wherein it comprises a control unit which implements the method of thermal management of a building according to claim 1.

14. System for thermal management of a building according to claim 13, wherein the control unit comprises a first module for estimating the exterior temperature over a future period, a second module for estimating the energy available in the generator for the period considered, a third module for learning the thermal characteristics of the building so as to model its thermal behaviour, a fourth module for determining the energy necessary for the building and a fifth module for thermal driving of the generator.

15. Building wherein it comprises a thermal management system implementing the thermal management method claim 1.