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Collection and analysis of RES calculation methods in EP calculation for new housing

ALTENER Proposal No 4.1030/Z/01-122/2001

Build-On-RES

Task 4 Framework for RES oriented

EP model building code

Final report

Principal author and editor:

C. Buscarlet, Centre scientifique et technique du bâtiment

Co-authors:

Milou Beerepoot (OTB)

Kirsten Engelund Thomsen (DBUR)

Roel de Coninck (3E)

Michelle Foster / Linda Sheridan (UoL)

Gerelle van Cruchten / Bart Poel (EBM)

Sophia-Antipolis, January 2004

Preface

This study describes the results of research into the Renewable Energy Sources (RES) calculation methods used in energy performance calculation for new housing as a means of encouraging the use of techniques making use of RES and stimulating CO2 reduction in the building sector.

This research is performed in the framework of the European project Build-On-RES, studying the possibilities of energy regulations in terms of encouraging the use of RES techniques and in stimulating technical sustainable innovations. The project ”Build-On- RES”, has been initiated by OTB Research Institute for Housing, Urban and Mobility Studies and is co-financed by the European Commission in the framework of the Altener programme. The project started in January 2002. It focuses on the promotion of renewable energy sources by means of energy performance regulations. The Build-On-RES project studies effects of energy performance regulations in The Netherlands, Denmark, United Kingdom, Belgium and France.

Content

1 RES calculation procedures collected 4

1.1 Introduction 4

1.2 Dutch EP calculation 5

1.3 Belgian method 5

1.4 German method 5

1.5 French method 6

1.6 Italian method 6

1.7 UK SAP calculation 6

1.8 Danish method 6

1.9 European standard EN 12976 7

2 COMPARISON OF THE METHODS 8

2.1 Application field 8

2.2 Input needed 9

2.3 Calculation procedure 10

2.4 Output given 12

3 Discussion 13

3.1 Regulation, standard and design tool 13

3.2 Harmonisation of solar energy calculation rules 13

3.3 Possible approaches for RES calculation 14

3.4 Choice of a method 15

4 Conclusion 17

References 18

Procedure sheets 19

Dutch solar thermal method 20

Dutch solar electrical method 21

Belgian solar thermal method 22

Belgian solar electrical method 23

German solar thermal method 24

French solar thermal method 25

French solar electrical method 26

Solar thermal method from the United Kingdom 27

EN 12976 based solar thermal method 28

RES calculation procedures collected

1 Introduction

Within Task 4 whose aim is: “framework for a RES (renewable energy sources) oriented energy performance EU Model Building Code”, task 4a1 consists in collecting and describing existing calculation methods dealing with RES for use in EP (energy performance) calculation in new housing in a database/ first part of a manual.

The starting point of this study is the work of the ENPER-TEBUC project. The ENPER project involves partners from 15 countries on the topic of energy performance standardization and regulation in the frame of the SAVE programme of the European Commission, DG TREN. The ENPER project was clustered with TEBUC ‘Towards an European Building Code’, another SAVE project of 3 countries which also deals with the issue of harmonization in European Building Codes. The Energy Performance (EP) standardisation and legislation is in many member states considered to be an attractive tool for increasing the energy efficiency of new buildings and existing buildings. Several countries have already an Energy Performance Regulation (EPR) in place and/or are preparing a new regulation. The project has studied the possibilities for designing harmonised building codes at the European level. Therefore the existing European building regulations were compared, extending existing work in that field.

The ENPER project mentions [1] five calculation methods for solar energy (at least for solar hot water) from the Netherlands, Flanders-Belgium, Germany, France and Italy. The renewable energy systems in the built environment considered in the ENPER report are solar thermal (domestic hot water production and space heating) and solar electrical grid connected systems (roofs and facades).

Heat pumps are not considered in the renewable energy part (§ 3.8) in the ENPER report, they are dealt with in § 3.7 "heating and cooling systems". Although geothermal and ambient energy is also considered in the Build-On-Res project, we concentrate here on solar thermal and electrical systems. Concerning heat pumps, the Technical Committee CEN/TC 228 ”Heating Systems in Buildings”, has edited in October 2003 a draft standard: prEN 14335 “Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies Part 2-2.2: Space heating generation systems - Heat pump systems”.

Other methods not mentioned in the ENPER report are considered in a first step, the SAP calculation from UK and the calculation for the Danish Labelling Scheme. This study includes also a proposal of EP calculation based on the European standard EN 12976 found in an ESTIF discussion paper written by Jan Erik Nielsen [2].

The application field of the various methods is given in Table 1.

|Method, country |solar system for tap water |solar system for space |photovoltaic system |calculation period |

| | |heating | | |

|NEN 5128, NL |yes |yes |yes |year |

|BE |yes |yes |yes |month |

|DIN 4701-10, DE |yes |yes |- |year |

|Th-C, FR |yes |yes |(yes) |month |

|UNI 8477-2, IT |yes |- |- |month |

|SAP 2001, UK |yes |- |- |year |

|DK |yes |yes |- |year, month |

|EN 12976, UE |yes |- |- |year |

Table 1 : calculation methods collected

All the methods are described in format sheets at the end of this report.

2 Dutch EP calculation

The Dutch standard for calculation of the energy performance coefficient for dwellings (NEN 5128) takes account of thermal solar energy systems for space heating and/or hot water and of photovoltaic electrical solar energy systems.

3 Belgian method

The Flemish “energy performance” method considers solar thermal and photovoltaic systems. It will be used in energy regulation in 2005.

The solar electrical method is similar to the Dutch method, with a monthly time step instead of yearly, while the solar thermal method looks different. The methods will be discussed in detail in chapter 3.

4 German method

A pre-standard DIN V 4701-10 for energy performance calculations for heating and ventilation systems was published in February 2001. A pre-standard is normally tested for 3 years before it becomes a standard. There is a new version of DIN V 4701-10 coming soon.

The pre-standard contains a calculation method to determine the energy performance of heating and ventilation systems in buildings or parts thereof.

In § 5.1.4 (Erzeugung der Wärme für die Trinkwassererwärmung) and § 5.3.4.1.3 (Solaranlagen zur Heizungsunterstützung) solar systems for hot water and space heating are taken into account. Heat pumps are also taken into account.

5 French method

The French "Règles Th-C" used to comply with the thermal regulation of new buildings RT 2000 contain a calculation method for solar systems for hot water and space heating.

The previous "Règles Th-C" (1993) contained already active solar calculations. The main differences are:

- now monthly calculation instead of annual calculation,

- simplification of input data.

Another addendum to Règles Th-C has been prepared for photovoltaic systems with the Dutch method as a starting point. It will be in force in 2004 or 2005.

6 Italian method

The Italian standard UNI 8477 parte 2a is a calculation method for performance of solar systems for space heating and/or hot water using air or water solar collectors. It is based on the F-chart method of Duffie & Beckman [3] (the well known simplified active solar calculation method) and gives data for the main Italian weather stations.

This method is a standard but it is not used in the Italian thermal regulation if we look at tables 5 and 6 in chapter 3 of the ENPER report [1]. Domestic hot water and active solar heating are not considered in the calculation for energy performance regulation, at least for the moment. However the standard is used as a reference method in the framework of regional solar energy promotion programmes[1].

7 UK SAP calculation

SAP 2001 is a calculation procedure that includes the Carbon Index Method (CIM). CIM is one of three alternative methods for energy regulations compliance, and is used throughout the UK (the other two compliance methods are prescriptive, being primarily based on envelope insulation values and boiler efficiency). The latest edition is SAP 2001, published in December 2001, operational in Scotland from 4 March 2002, and in England and Wales from 1 April 2002.

SAP stands for Standard Assessment Procedure. It produces an energy cost rating (the SAP rating) and a carbon index (the CI) for a dwelling, based on calculated annual energy for space and water heating. Solar hot water is taken into account.

8 Danish method

In the Danish Labelling Scheme for small buildings, gains from active solar thermal energy are calculated. The result of the calculation is used for energy rating.

The method is not used for energy regulations, but it is merely being used for energy certification of new and existing buildings (see more details in the report of task 4b1).

9 European standard EN 12976

The European standard EN 12976 “Factory made solar DHW system tested according to EN 12976 Thermal solar systems and components - Factory Made systems – Part 1 General requirements – Part 2 Test methods “ gives the energy performance of a particular RES system (Factory made solar DHW system) as Jan Erik Nielsen notes in an ESTIF discussion paper [2]. He proposes to use the standard as a method for calculating the contribution to energy savings in building from a solar water heater.

This method is a stand-alone method while the others (except UNI 8477-2) are integrated in more general methods.

COMPARISON OF THE METHODS

This study concerns energy performance methods being used as energy regulations for new buildings. That implies that only the Dutch, the Belgian, the German, the French and the English method should be discussed. We consider also the project of a method based on EN 12976 as an alternative.

The main comparison elements between the methods are:

- the application field,

- the input needed,

- the calculation procedure,

- the output given.

The 3 solar electrical PV methods are very similar and we focus, for the comparison on the solar thermal methods.

1 Application field

We have solar thermal methods and solar electrical (photovoltaic) methods. As far as solar thermal methods are concerned there are hot water systems and combi-systems (space heating + domestic hot water).

Then for a given application, the field can be restricted for two reasons :

1) a reason linked to regulation purpose – for instance PV method applying to installation described in the building permit,

2) a reason linked to the calculation procedure – for instance the f-chart method is valid only if the storage losses are under a minimum, the EN 12976 based method deals only with factory made solar DHW systems.

| |NEN 5128 |Flemish |DIN 4107 |Th-C |SAP |EN 12976 |

| |NL |method |D | | |UE |

| | |B | |F |UK | |

|Limitation due to the | | | |Yes | |Yes |

|calculation procedure | | | | | | |

Table 1 : Limitation to application field due to the calculation procedure

An objective could be that the application field is restricted only for regulation reason. However a restriction due to the procedure, for instance a maximum for the storage losses, can be also good in the regulation point of view.

2 Input needed

| |NEN 5128 |Flemish |DIN 4107 |Th-C |SAP |EN 12976 |

|Input data |NL |method |D | | |UE |

| | |B | |F |UK | |

|Solar collector area |Yes |Yes |Yes |Yes |Yes |Yes |

|Orientation and pitch |Yes |Yes |Yes |(5) | | |

|Collector characteristics|(1) |(2) |Yes (3) |Yes (3) | |(4) |

|Shading geometry |Yes |Yes | | | | |

|Heat demand |Yes |Yes |Yes |Yes |Yes |Yes |

|Storage specification | | |Yes |Yes | | |

|Temperature specification| | |Yes |Yes | | |

|Location | | | |Yes | |Yes |

|Others | | |(6) |(7) | | |

Table 2 : Comparison of the input data

1 - The manufacturer can demonstrate the efficiency of the system

2 – If they are known, they can be used as input in an adapted simulation programme

3 – There are default values

4 – EN 12976 gives the characteristics of a solar water heater

5 – Only whether it is optimum or not (to apply a reduction factor)

6 – Depending on the category of system

7 - Heat exchanger efficiency etc. (optional)

The number of the input data depends on the level of detail the system is represented, which is also the complexity of the method. The SAP method with only the solar panel area and the heat demand as input is the simplest method.

Below is shown the list of inputs given by Jan Erik Nielsen in his already quoted paper [2] for “non EN 12976 systems”:

1) location (from list)

2) collector type/name (from list of tested/keymarked/national-marked collectors including maybe a “dummy”, alternatively the main collector parameter values (Area, η0, a1, a2) could be given)

3) number of collector modules (1,2,3,…)

4) application type

5) orientation (tilt, azimuth)

6) basic energy system (oil, gas, elec, …)

7) load (based on heated area, tank volume, no. rooms, “EU-tapping cycles”?..)

About the collector characteristics (input n° 2) we can mention that a regulation tool may advantage a certified or marked product. For instance the French regulation applies a penalty to some product data if the product is not certified.

The system characteristics (storage volume etc.) are not in the list. The system is supposed to be well designed for a given solar panel area.

The basic energy system was not mentioned in table 2 but it is part of the more general methods in which the RES calculation takes place.

3 Calculation procedure

The methods above use generally monthly or yearly formulas, f-chart of solar load ratio (SLR) like. A SLR method use in a simple formula the ratio solar energy available over load. F-chart is a well known simplified method for active solar systems [3] using correlation formulas.

| |NEN 5128 |Flemish |DIN 4107 |Th-C |SAP |EN 12976 |

|Calculation procedure |NL |method |D | | |UE |

| | |B | |F |UK | |

|Solar load ratio |Yes |Yes | | |Yes | |

|f-chart | | | |Yes | | |

|Other correlation | | |Yes | | | |

|Simulation model | |(1) |(1) | | |(2) |

Table 3 : Calculation procedures

1 – The use of an adapted simulation programme is optional

2 – A simulation model is applied inside the test procedure to give the performance test results (day-by-day method or DST method)

No simulation model is used in an EP calculation part of a thermal regulation in force now. However the option of using simulation programme is offered by DIN 4107 which gives the requirement for the simulation programme. This option is also mentioned for the future Belgian regulation and the EN 12976 gives the test results using one of two detailed calculation programmes (hourly and daily).

When two methods can accept the same types of data and output, we can compare the results. This is the case for SAP and NEN 5128. We have calculated the yearly solar contribution by m² of solar collector for various solar panel area with the hypothesis of hot water energy requirement equal to 10 GJ. The results are shown in the following figure.

[pic]

Figure 1: Comparison of the results of NEN 5128, SAP 2001

The Dutch curve is above the other one, perhaps because of a bigger implicit solar irradiation. This raises the issue of the correctness of a calculation procedure. If a procedure gives better results it may encourage more the use of RES but it risks to be not enough realistic. In the past, CSTB who wanted to be realistic, developed some methods that were too pessimistic from the point of view of solar designers.

In figure 1, the NEN 5128 curve is less regular because the efficiency of the solar system is given by a table and not by a single formula. Tables are convenient especially for hand calculation. They were widely used in the former French methods. When possible, formulas are better. They give more regular results and they can be computerised more easily.

4 Output given

The results show more or less directly the amount of energy contributed to by the solar system - the solar fraction is the energy supplied by the solar part of a system divided by the total system load (ISO 9488). Sometimes the parasitic energy is given.

Then the results are often reintroduced in the general method to get the final result and the contribution of RES is not explicitly given.

| |NEN 5128 |Flemish |DIN 4107 |Th-C |SAP |EN 12976 |

|Output |NL |method |D | | |UE |

| | |B | |F |UK | |

|Explicit contribution of |(1) |(1) | | |(1) | |

|RES | | |Yes | | |Yes |

Table 4 : Output

1: When making the EP-calculation the result will be visible to the architect or engineer, but the final result is only one number which gives only an overall impression of the energy performance of the building.

Discussion

1 Regulation, standard and design tool

We have distinguished regulation method and design tool (or performance prediction tool). A standard can be used in regulation but standard does not mean regulation. SAP is only a regulation method while the standard UNI 8477 is a design tool – with for instance the possibility to derive the optimum storage volume, this is why we have not kept it for the study. If a regulation method is complex and can handle various configurations, people can have the idea of using it for design purpose.

In the former French "LHPE-LS" method there was a warning "This method should not be used for performance prediction". As it is very simple and as it doesn't claim to predict real results, the SAP method does not need such a warning.

2 Harmonisation of solar energy calculation rules

The ENPER report [1] raises the question how solar energy calculation rules can be harmonised.

It mentions a first step which is "to apply the same databases for solar radiation, being the most important source for the calculation. The recently published European Solar Radiation Atlas (ESRA, ISBN:2-911762-21-5) could be that source." I don't see any particular problem there. Anyway the number of solar data is limited : 1 figure for SAP, 1 for NEN 5128, 3 for Th-C (there are 3 climatic zones)…

The second step is connected to the aim of the Buil-On-Res project: "A second step could be to agree on a simplified calculation method that contains the principle parameters for reduction and build a database that contains the essential parameters and calculation reduction factors, to describe the solar thermal and solar electrical systems. Agreement should be made on the utilisation of solar energy. How should solar thermal energy for hot water (mainly south European countries) and for space heating be represented in a general calculation rule?"

After having reviewed various methods in the previous chapter, we can describe possible approaches.

3 Possible approaches for RES calculation

Stand-alone method or integrated method

A stand-alone method, as proposed by Jan Erik Nielsen [2] has the advantage that it could be agreed upon at the European level. However there is anyway a need to include RES in more general EP calculation. Also RES techniques should not be considered in a building without looking at energy savings.

Level of detail

The main point is here. In the working groups who develop RES calculation for regulation purpose there are always people willing to improve the method taking account of more parameters and people willing to keep a simple an easy to use method, with the risk of deviate from reality.

The question raised are especially:

- the number of geographic zones (one for SAP, NEN 5128… three for the solar thermal addendum to Th-C but five in the draft solar photovoltaic addendum to Th-C),

- orientation and shading – from no taking into account as in SAP to a calculation as in NEN; in the solar thermal addendum to Th-C a simple way has been agreed as shown below

|Where collectors face between south-east and south-west with a tilt angle between 40° and 50° from the horizontal and are not masked by any |

|obstacles, the values for the monthly irradiation on collector plane are as given in a table below for the three climatic zones. In all other|

|cases, a coefficient of reduction of 0.8 is applied to the values in the table, provided that the direction the collectors is included |

|between -90 and +90° (south = 0°) and the average height of obstacles on the horizon is less than 20°. |

- the solar collector characteristics – except in SAP they are taken into account but there are sometimes default values,

- the installation characteristics - storage volume for instance.

However the calculation module for a solar (or other RES) system has to be consistent with the calculation of the conventional systems in the regulation method. For instance, as the "règles Th-C" are rather detailed, the solar thermal addendum could not be too simple. All the same, it is more simple than the previous one (1993). In "règles Th-C 93" you could even, if you wanted, specify the thermal capacity of the transfer fluid and the heat transfer coefficient of the exchanger.

Calculation procedure

Simple formula or simulation model ? For the moment the methods in force use simple formulas. The way proposed by the Belgian “energy performance” method may be interesting: “When the design of the STS and the characteristics of each of the components is known, the monthly useful energy production can be calculated with an adapted simulation programme”.

The German standard allows the use of commercially available simulation programs, which fulfil the requirements specified in a normative annex. A simulation programme is considered as validated if it predicts the annual yield of a reference system with an error less than 3 %.

Also the calculation method and its time step, yearly or monthly... have to be consistent with the rest of the EP calculation.

4 Choice of a method

The main choices that will have to made by a member state are based on the complexity of calculation. Complexity of a calculation can be expressed in a number of items such as the first three in the following table. The last three concern the application; it seems interesting to know the extent to which a calculation method is similar to the one of another member state or if a method part of an energy performance calculation can be adapted to another EP calculation.

| |A |B |C |D |

|1. Time frame |year |month |day |hour |

|2. Detail of input |1 input parameter |2 or 3 parameters |possibility of | input for |

| |(collector area - the |including at least |taking account |detailed simulation |

| |heat demand is already |1 key characteristic |of all the main |(may include |

| |known from the rest of EP|of the system |system parameters |dynamic |

| |calculation) |(collector efficiency…) |(like storage volume,...)|characteristics) |

|3. Calculation |key figures |correlation formulas |simulation | |

|principle | | | | |

|4. Application within |original method |method similar to the one|method using well known | |

|EU | |of another member state |formulas | |

|5. Compatibility |Stand alone method |the method can be adapted|difficult to adapt to | |

| | |to another EP calculation|another EP calculation | |

|6. Applicability |New dwellings |Existing dwellings | | |

Table 5 : features of calculation method on a scale of 1 to 4

On the following table are scored these six features for the various calculation methods of solar hot water we have studied.

| |NEN 5128 |Flemish |DIN 4107 |Th-C |SAP |EN 12976 |

| |NL |method |D | | |based |

| | |B | |F |UK |EU |

|1. Time frame (of input) |A |B |A |B |A |A |

|2. Detail of input |B |B |C |C |A |B |

|3. Calculation principle |B |B, C |B, C |B |B |A |

|4. Application within EU |B |B |A |C |A |A |

|5. Compatibility |B |B |C |B |B |A |

|6. Applicability |A |A |A |A |A, B |A, B |

Table 6 : scores of the methods

The discussion is still open about how detailed/complex a calculation procedure should be. Some state that the calculation procedure should be as detailed as possible, as long as this would be covered by an easy-to-use user interface. Others state that we have to be aware that we are talking about a policy instrument that doesn't need to be very detailed, as long as it is possible to compare buildings and to set a regulation level. Another thing is that some member states already use Energy Performance methods and may tend to look for additional calc. proc., such as RES procedures, that suit their current calculation principles (so detailed EP calc. would plead for detailed RES calc.).

Then the features of the best method depend on the already existing procedures in a member state and the ideas that exist in a member state about calculation procedures for building regulations.

Conclusion

We have collected and described existing calculation methods dealing with RES (Renewable energy sources), especially solar, for use in EP (energy performance) calculation in new housing, for regulation purpose.

We hope this work can be useful to those who wish to implement such methods in their country.

References

1. Energy Performance of Buildings - Calculation procedures used in European countries, SAVE programme, ENPER project report CSTB-DDD-AGE n° 02-126R

2. Outline of a methodology for calculating the contribution to energy savings in buildings from solar heating (and cooling) systems - Co-ordinated implementations of the EPD directive with respect to solar thermal systems

ESTIF internal discussion paper, 2nd draft, Jan Erik Nielsen, 22 August 2003

3. Solar Heating Design by the F-chart Method By William A. Beckman, Sanford A. Klein, John A. Duffie, New York, 1977

Annex

Procedure sheets

Dutch solar thermal method

|Procedure name |

|Contribution of a thermal solar energy system to domestic hot water in Dutch standard NEN 5128 (Energy Performance Regulations since 1996) |

|Application field |

|Solar thermal system for domestic hot water |

|Input |

|Area of solar collectors, Aze m² |

|Solar collector pitch and orientation, shading |

|Gross heat demand for domestic hot water, MJ/year |

|(Optional : efficiency of the solar thermal system demonstrated by a quality label of the manufacturer) |

|Calculation |

|Solar collector yield = Qze = ηze * (zjaar * rjaar * Aze * 2800) |

|The efficiency of the solar thermal system ηze can be found in a table as a function of the proportion of solar collector yield and domestic |

|hot water demand (unless it is an input data) |

|The product of orientation factor and shadowing factor zjaar * rjaar for most common situations can be found in a table as a function of |

|orientation and tilt of the solar collectors |

|The calculation value 2800 is the yearly accumulated intensity of the captured radiation on a vertical surface that is south-oriented (MJ/m2)|

|Output |

|Solar collector yield (MJ/year), to be subtracted from the gross heat demand for domestic hot water |

[pic]

Dutch solar electrical method

|Procedure name |

|Contribution of photovoltaic electrical solar systems in Dutch standard NEN 5128 (Energy Performance Regulations since 1996) |

|Application field |

|PV system considered in the building permit to be a part of the building |

|Input |

|Area of the PV panels, Apv m² |

|Solar panels pitch and orientation, shading |

|Watt peak capacity or type of PV panel (mono or multi cristal etc. then the peak capacity is given in a table) |

|System type (central inverter or AC module, integrated in roof or detached etc.) |

|Primary energy use for lighting, fans, cooling and other electricity appliances, MJ/year |

|Calculation |

|Reduction of the primary energy consumption due to PV systems Qprim;pv = min(Qpv; Qp) |

|Qp = sum of primary energy use for lighting, fans, cooling and other electricity appliances |

|Qpv contribution of the PV system = RFpv* Spv* Cs,pv* Qpv;opv/(1000 * ηel) MJ/year |

|(el = the efficiency of the Dutch electricity generation, a fixed figure determined to be 0,39 |

|Spv = PV / Apv and Qpv;opv = zjaar * rjaar * Apv * 2800 |

|Qpv;opv = the yearly quantity of solar radiation captured by the PV panels of system in MJ |

|RFpv = the reduction/correction factor according to a table as a function of the system type (central inverter or AC module, integrated in |

|roof or detached etc.) |

|Spv = Watt peak capacity per m2 PV panel |

|PV = the sum of the Watt peak capacities of the panels of the PV system, determined according to the Dutch standard NEN 10904-1 |

|The product of orientation factor and shadowing factor zjaar * rjaar for most common situations can be found in a table as a function of |

|orientation and tilt of the solar panels |

|Cs,pv i = the correction factor for the influence of shadowing on the PV panels, given in a table, function of rjaar |

|The calculation value 2800 is the yearly accumulated intensity of the captured radiation on a vertical surface that is south-oriented (MJ/m2)|

|Output |

|Reduction of the primary energy consumption due to photovoltaic solar energy system in MJ/year |

Belgian solar thermal method

|Procedure name |

|Monthly useful energy production of a solar thermal system (STS) in the Flemish “energy performance” method |

|Application field |

|Solar thermal systems for space heating and domestic hot water (DHW) (system 1) |

|Solar thermal systems for hot water (system 2) |

|Input |

|Area of solar collectors, Aze m² |

|Solar collector pitch and orientation, shading geometry (masks…) |

|Yearly, monthly gross heat demand for DHW, Qbehoefte, bruto,jaar,tap, Qbehoefte, bruto,ma,tap MJ |

|Yearly, monthly gross heat demand for space heating Qbehoefte, bruto,jaar,verw , |

|Qbehoefte, bruto,ma,verw (for system 1) |

|Optional : characteristics of components and installation for calculation with an adapted simulation program (not yet defined) |

|Calculation |

|Monthly energy collection by STS: [pic] (MJ) |

|Qzon,ma : monthly solar irradiation on collector plane in MJ/m², calculated by formulas taking account of orientation, tilt and shading |

|effects. |

|The monthly useful energy production of the STS is |

|for system 1 : |

|[pic](MJ) |

|with: |

|ηze,ma,verw+tap monthly average efficiency of STS (constant) calculated as: |

|[pic] |

|Qze,opv,jaar the yearly energy collection by the solar thermal system (= sum of the 12 Qze,opv,ma) |

|The monthly useful contribution of the STS is distributed over space heating and hot water in proportion of energy demand (Qbehoefte, |

|bruto,ma,verw and Qbehoefte, bruto,ma,tap) |

|for system 2 : |

|[pic] (MJ) |

| |

|The monthly average efficiency of the STS ηze,ma,tap is as follows: |

|[pic] |

|Output |

|The monthly useful energy production to be subtracted from the gross heat demand before conversion to net heat demand by use of the production |

|efficiency. At the end, the total energy demand is converted into primary energy using a conversion factor (1 for gas and gas oil, 2.5 for |

|electricity). |

Belgian solar electrical method

|Procedure name |

|Contribution of photovoltaic electrical solar systems |

|Monthly useful energy production of a solar thermal system (STS) in the Flemish “energy performance” method |

|Application field |

|Building integrated PV system |

|Input |

|Area of the PV panels, Apv m² |

|Solar panels pitch and orientation, shading geometry (masks…) |

|Peak power per m² panel in kW Spv determined following NBN-EN-CIE 60904-1 or type of PV panel (mono or multi cristal etc. then Spv is given |

|in a table) |

|System type (central inverter or AC module, integrated in roof or detached etc.) |

|Calculation |

|The monthly useful primary energy contribution of a building integrated PV system Qbijdrage,nuttig,ma, pv is calculated as follows: |

|[pic] (MJ) |

|with aprimair,el Conversion factor to primary energy for electricity = 2.5. |

| |

|The monthly useful energy contribution of a building integrated PV system can be calculated as follows: |

|[pic] (MJ) |

|RFpv the reduction/correction factor according to a table as a function of the system type (central inverter or AC module, integrated in |

|roof or detached etc.) |

|rpv,ma the shading coefficient, calculated as for thermal application |

|qzon,ma the monthly average solar incident radiation on the not shaded PV-system, in W/m²; |

|tma the length of the month in Ms, . |

|cpv correction coefficient for shading (specific for PV application) : [pic] |

|Output |

|Reduction of the primary energy consumption due to photovoltaic solar energy system in MJ/month |

German solar thermal method

|Procedure name |

|DIN V 4701-10: Februar 2001 Bewertung der Anlagentechnik |

|§ 5.1.4.1.1 Deckungsanteile für Solaranlagen zur Trinkwassererwärmung |

|(contribution of solar systems to domestic hot water production) |

|§ 5.3.4.1.3 Solaranlagen zur Heizungsunterstützung |

|Application field |

|Solar thermal systems for domestic hot water and space heating |

|Input |

|Area of solar collectors AC |

|Collector characteristics (η0, k1, k2, IAM50, C, the standard gives also default values) |

|Solar collector pitch and orientation |

|Storage volume |

|Storage temperature |

|Heat demand for domestic hot water, Q*TW [kWh/y] |

|Heat demand for space heating |

|…(depending on 4 categories below) |

|Calculation |

|Four categories: |

|1 Small hot water systems |

|2 Large hot water systems |

|3 Small space heating systems |

|4 Large space heating systems |

|Example for category 1 - The yearly yield (kWh) of the solar system for domestic hot water is given by: |

|QTW,sol = QSYS * fNA * fslr * fd,sol *fS,Vsol * fS,Vaux * fS, loss |

|QSYS energy yield of the solar plant for reference conditions [ kWh/y ] : |

|QSYS = (271η0 - 18,8 k1 - 653 k2 + 172 IAM50 - 0,792 C - 20,7)* AC |

|fNA correction factor for inclination and orientation [ - ], given in table |

|fslr ’ − 2 .73 – 0.6 ln(AC/Q*TW) : solar load ratio coefficient [ - ] |

|fd,sol and fS, loss correction factors for the losses of the solar circuit and store [ - ] given in tables |

|fS,Vsol and fS,Vaux correction factors for the solar and auxiliary storage volumes [ - ] given in tables |

|Simplified formula for combisystems (space heating + domestic hot water): |

|10 % solar fraction for space heating if collector area is at least 1.8 the reference one for the hot water needs |

|Possibility of using reference simulation programmes which fulfil requirements given in the standard |

|Output |

|Yearly yield of the solar system for domestic hot water and space heating |

French solar thermal method

|Procedure name |

|Addenda to French Th-C Rules |

|Solar thermal installations |

|Application field |

|· solar water heaters (factory made in compliance with standard EN 12976), |

|· solar hot-water systems (custom built in compliance with standard EN 12977) |

|· solar space heating and hot-water systems with solar collectors linked to separate heating and hot-water storage tanks, |

|· solar space heating and hot-water system with solar collectors linked to heating floor and storage tank for domestic hot water |

|Excluded: outside close coupled solar water heaters - especially ICS, solar combi-systems other than the two referred to above, air solar |

|collector systems, heat pumps coupled to solar collectors |

|Input |

|Product characteristics: solar collectors (as in EN 12975), solar water heaters (as in EN 12976), storage tank (volume and loss coefficient) |

| |

|Installation characteristics: collector orientation and tilt, solar circuit length and insulation, solar tank to auxiliary unit length and |

|insulation, pumps power, solar heating floor characteristics (area, diameter and spacing of the tubes) |

|Other |

|Climatic zone (H1, H2 or H3) |

|Monthly domestic hot water (DHW) demand + distribution losses and, if solar space heating system, monthly heating requirements + net |

|distribution losses and losses from the back of the emitters |

|Calculation |

|Solar fraction F = aY + bX + cY² + dX² + eY3 +fX3 (f-chart method) |

|X: captation losses / L (with correction factor for storage volume) |

|Y: solar energy available / L |

|L: monthly heating load for DHW and/or space heating |

|Reduction coefficient for auxiliary system ca = 4 (1 - FDHW) if FDHW > 0.75 |

|The monthly solar irradiation on collector is given in a table for orientation between south-east and south-west and tilt between 40° and |

|50°, for the three climatic zones; for orientation between east and west and any tilt angle, a reduction coefficient of 0.8 is applied. |

|Output |

|Solar fraction for DHW and/or space heating demand (monthly) |

|Distribution losses between solar system and auxiliary unit (monthly) |

|Reduction coefficient for auxiliary system (monthly) |

|Solar parasitic energy (monthly) |

[pic]

French solar electrical method

|Procedure name |

|Addenda to French Th-C Rules |

|Solar photovoltaic systems (applicable 2004 ?) |

|Application field |

|Grid connected (without storage) PV system considered in the building permit to be a part of the building |

|Input |

|Area of the PV panels, Apv m² |

|Solar panels pitch and orientation |

|Watt peak capacity mesured by accredited laboratory or type of PV panel (mono or multi cristal etc.) |

|Geographic zone (department n°) |

|Floor area of the building (give the maximum PV contribution) |

|Calculation |

|PV system yield Epv = Hi . P0 . Rp [kWh/year] |

|Hi: incident solar energy on panel plane, given by tables (specific for PV), as a function of zone, orientation and tilt of the solar panels |

|P0: Watt peak capacities of the panels, according to the French standard NF C 57-100 |

|Rp: the reduction/correction factor according to a table as a function of the system type (especially as far as ventilation is concerned) |

|Output |

|The yearly PV contribution is divided by the energy conversion coefficient 2,58 then subtracted from the building consumption (C coefficient)|

Solar thermal method from the United Kingdom

|Procedure name |

|SAP |

|The Government’s Standard Assessment Procedure for Energy Rating of Dwellings |

|2001 EDITION |

|Area of solar panel, m² |

|Yearly hot water usage (GJ/year, at point of use, depending on floor area |

|Application field |

|Solar water-heating systems with solar panels and hot water cylinder |

|Input |

|Area of solar panel, m² |

|Yearly hot water usage (GJ/year, at point of use, depending on floor area) |

|Calculation |

|LR = Load ratio = (Hot water usage) ÷ (1.3 x Area of solar panel) |

|Solar input = 1.3 x Area of solar panel x [LR / (1 + LR)] |

|Output |

|Solar input (GJ/year), |

|to be subtracted from the sum |

|hot water usage + distribution losses + storage losses + primary circuit (not solar) and keep-hot losses |

EN 12976 based solar thermal method

|Procedure name |

|Method based on EN 12976 proposed by Jan Erik Nielsen [2] |

|Application field |

|Factory made solar DHW system tested according to EN 12976 Thermal solar systems and components - Factory Made systems – Part 1 General |

|requirements – Part 2 Test methods |

|Input |

|Result of the test according to EN 12976-2 |

| |

|Qd: Demand in MJ/y (design load) |

|QL: Heat delivered in from solar system in MJ/y |

|Qaux,net: Net auxiliary energy demand in MJ/y |

|Qpar: Parasitic energy (pump, controller) in MJ/y |

| |

|Q’s are values corresponding to a climate representative to the country/region of the building |

|Calculation |

|The annual energy performance is |

|Solar-plus-suplementary-systems: (Qd – Qaux, net – Qpar)/(b |

|Solar-only / solar preheat systems: ((QL-Qpar)/(b |

|where (b is the efficiency (close to the summer efficiency) of the basic heat production, example: |

|Electricity: 70%, Gas: 65%, Oil: 60%, Biomass: 50%, Heat pump (COP): 2 (a very rare combination in residential houses), District heating: 65%|

|(in users installation – taking into account also the external pipe heat losses brings it down to maybe 20%?!) |

|Output |

|The annual energy performance expressed in the energy used by the auxiliary system |

-----------------------

[1] “Programma solare termico - bandi regionali”, Gazzetta Ufficiale n. 229 del 30 Settembre 2002

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