SIST EN 17522:2023
(Main)Design and construction of backfilled and grouted borehole heat exchangers
Design and construction of backfilled and grouted borehole heat exchangers
This document covers standardization in the field of geological and environmental aspects, design, drilling, construction, completion, operation, monitoring, maintenance, rehabilitation and decommissioning of borehole heat exchangers for uses of geothermal energy.
The direct expansion and thermal syphon techniques are excluded from this document
Planung und Bau von Erdwärmesonden
Dieses Dokument befasst sich mit der Normung von Erdwärmesonden für geothermische Anwendungen unter geologischen und Umweltaspekten und deckt dabei die Bereiche Auslegung, Bohrung, Ausführung der Sonde, Fertigstellung der Anlage, Betrieb, Überwachung, Wartung, Sanierung und Stilllegung ab.
Techniken mit direkter Ausdehnung und Thermosiphonen werden in diesem Dokument nicht behandelt.
Conception et construction de sondes géothermiques verticales comblées et remplies de coulis
Le présent document concerne la normalisation des aspects géologiques et environnementaux de la conception, de la construction, du fonctionnement, de la surveillance, de la maintenance et du démantèlement des échangeurs géothermiques fermés (sondes géothermiques verticales) remplis de coulis, pour les applications en géothermie.
Le présent document est uniquement applicable aux forages comblés et remplis de coulis, et non aux forages remplis d’eau souterraine.
Les techniques de détente directe et de thermosiphon sont exclues du présent document.
Zasnova in zgradba zasutih in z malto zalitih vrtinskih toplotnih izmenjevalnikov
Ta dokument zajema standardizacijo na področju geoloških in okoljskih vidikov, projektiranja, vrtanja, gradnje, izvedbe, delovanja, spremljanja, vzdrževanja, obnove in razgradnje izmenjevalnikov toplote v vrtinah za izkoriščanje geotermalne energije.
Tehnike neposrednega širjenja in termosifonske tehnike so izključene iz tega dokumenta.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 17522:2023
01-junij-2023
Zasnova in zgradba zasutih in z malto zalitih vrtinskih toplotnih izmenjevalnikov
Design and construction of backfilled and grouted borehole heat exchangers
Planung und Bau von Erdwärmesonden
Conception et construction de sondes géothermiques verticales comblées et remplies de
coulis
Ta slovenski standard je istoveten z: EN 17522:2023
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
SIST EN 17522:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN 17522:2023
---------------------- Page: 2 ----------------------
SIST EN 17522:2023
EN 17522
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2023
EUROPÄISCHE NORM
ICS 07.060; 27.190; 91.140.10
English Version
Design and construction of backfilled and grouted
borehole heat exchangers
Conception et construction de sondes géothermiques Planung und Bau von Erdwärmesonden
verticales comblées et remplies de coulis
This European Standard was approved by CEN on 23 January 2023.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17522:2023 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
Contents Page
European foreword . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Geological and environmental aspects . 10
4.1 General. 10
4.2 Geological and hydrogeological risks . 11
4.2.1 Artesian aquifers . 11
4.2.2 Stacked aquifers with different groundwater potential . 11
4.2.3 Groundwater and soil chemistry . 11
4.2.4 Gas occurrence . 11
4.2.5 Ground stability . 11
4.2.6 Contrasting geological sequence (Alternated bedding) . 12
4.2.7 Karst geology . 12
4.2.8 Frost susceptibility . 13
4.2.9 Groundwater protection area . 13
4.3 Anthropogenic risks and constraints . 13
4.4 Environmental aspects . 13
4.4.1 General. 13
4.4.2 Influence on groundwater . 13
4.4.3 Environmental impact due to construction works . 14
5 System description . 15
5.1 General. 15
5.2 Borehole heat exchanger . 15
5.3 Horizontal piping . 17
5.4 Manifolds . 17
2
---------------------- Page: 4 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
5.5 Thermal plant . 18
6 Materials . 18
6.1 General properties . 18
6.2 Materials . 18
6.2.1 Polymeric materials . 18
6.2.2 Connection methods . 20
6.2.3 Metallic materials . 21
6.3 Heat transfer fluid . 21
6.4 Backfilling materials . 22
6.4.1 General . 22
6.4.2 Grouting material . 22
6.4.3 Other backfilling materials requirements . 23
6.5 Component selection criteria . 23
6.5.1 General . 23
6.5.2 BHE loops . 23
6.5.3 Horizontal pipes . 24
6.5.4 Manifolds . 24
6.5.5 Heat transfer fluid . 24
7 Design . 24
7.1 Steps of design . 24
7.2 Sizing . 25
7.2.1 General . 25
7.2.2 General methodology . 26
7.2.3 Thermal properties of the ground . 29
7.2.4 Thermal Response Test (TRT) . 30
7.2.5 Calculation and modelling procedure . 37
7.2.6 Simulation . 38
7.2.7 Hydraulic design . 39
3
---------------------- Page: 5 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
8 Construction . 40
8.1 General. 40
8.2 Site preparation and planning . 40
8.3 Drilling . 41
8.3.1 General. 41
8.3.2 Drilling diameter . 41
8.3.3 Drilling fluid . 41
8.3.4 Monitoring and documentation of the drilling process . 41
8.4 Borehole heat exchanger loop . 42
8.5 Borehole heat exchanger loop installation . 42
8.6 Backfilling and grouting procedure . 43
8.6.1 General. 43
8.6.2 Grouting procedure . 43
8.6.3 Other backfilling procedure. 44
8.7 Horizontal piping . 44
8.8 Testing and checking of BHE – Leakage, flow, grouting, geophysical measurements . 45
8.9 Manifolds . 45
9 Start-up . 46
9.1 General. 46
9.2 Heat transfer fluid . 46
9.3 Filling of the system . 46
9.4 Drying of new buildings . 46
9.5 Commissioning . 46
9.6 Documentation . 47
10 Operation, monitoring and maintenance . 47
10.1 Operation . 47
10.2 Monitoring . 47
10.2.1 General. 47
4
---------------------- Page: 6 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
10.2.2 Temperature . 48
10.2.3 Pressure . 48
10.2.4 Flow rate . 48
10.3 Maintenance . 48
11 Renovation . 49
12 Decommissioning . 49
12.1 General . 49
12.2 Heat transfer fluid . 49
12.3 Borehole heat exchangers . 49
12.3.1 Backfilled boreholes . 49
12.4 Horizontal pipes . 50
12.5 Documentation . 50
Annex A (informative) Insulation of horizontal piping . 51
Annex B (informative) Example simulation time . 52
B.1 General . 52
B.2 Single house, unbalanced energy design. 52
B.3 Field of 30 houses with an unbalanced design . 53
B.4 Field with 400 houses with an unbalanced design . 54
B.5 Conclusion . 54
Annex C (informative) Commissioning checklist . 55
Annex D (informative) Examples of thermal conductivity and volumetric - heat capacity of the
underground . 57
Annex E (informative) Main drilling methods . 59
Bibliography . 61
5
---------------------- Page: 7 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
European foreword
This document (EN 17522:2023) has been prepared by Technical Committee CEN/TC 451 “Water wells
and borehole heat exchangers”, the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2023, and conflicting national standards shall
be withdrawn at the latest by October 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
6
---------------------- Page: 8 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
1 Scope
This document covers standardization in the field of geological and environmental aspects, design,
construction, operation, monitoring, maintenance and decommissioning of grouted borehole heat
exchangers for uses in geothermal energy systems.
This document is only applicable for backfilled and grouted boreholes, it is not applicable for
groundwater-filled boreholes.
Direct expansion and thermal syphon techniques are excluded from this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1057, Copper and copper alloys — Seamless, round copper tubes for water and gas in sanitary and
heating applications
EN 1254-2, Copper and copper alloys —Plumbing fittings — Part 2: Compression fittings for use with copper
tubes
EN 1254-3, Copper and copper alloys — Plumbing fittings — Part 3: Compression fittings for use with
plastics and multilayer pipes
EN 1254-7, Copper and copper alloys — Plumbing fittings — Part 7: Press fittings for use with metallic tubes
EN 1254-8, Copper and copper alloys — Plumbing fittings — Part 8: Press fittings for use with plastics and
multilayer pipes
EN 1965-2, Structural adhesives — Corrosion — Part 2: Determination and classification of corrosion to a
brass substrate
EN 10216-5, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 5: Stainless
steel tubes
EN 12201-1:2011, Plastics piping systems for water supply, and for drainage and sewerage under pressure
— Polyethylene (PE) — Part 1: General
EN 12201-2, Plastics piping systems for water supply, and for drainage and sewerage under pressure —
Polyethylene (PE) — Part 2: Pipes
EN 12201-3, Plastics piping systems for water supply, and for drainage and sewerage under pressure —
Polyethylene (PE) — Part 3: Fittings
EN 12201-5, Plastics piping systems for water supply, and for drainage and sewerage under pressure —
Polyethylene (PE) — Part 5: Fitness for purpose of the system
EN 12449, Copper and copper alloys — Seamless, round tubes for general purposes
EN ISO 15875-1, Plastics piping systems for hot and cold water installations — Crosslinked polyethylene
(PE-X) — Part 1: General (ISO 15875-1)
7
---------------------- Page: 9 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
EN ISO 15494, Plastics piping systems for industrial applications — Polybutene (PB), polyethylene (PE),
polyethylene of raised temperature resistance (PE-RT), crosslinked polyethylene (PE-X), polypropylene (PP)
— Metric series for specifications for components and the system (ISO 15494)
EN ISO 22391-1, Plastics piping systems for hot and cold water installations — Polyethylene of raised
temperature resistance (PE-RT) — Part 1: General (ISO 22391-1)
EN 12168, Copper and copper alloys — Hollow rod for free machining purposes
EN ISO 1127, Stainless steel tubes — Dimensions, tolerances and conventional masses per unit length (ISO
1127)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
aquifer
water-bearing geological layer comprising permeable rock, fractures or unconsolidated materials
(gravel, sand, or silt)
Note 1 to entry: an aquifer can be fully or partly saturated.
Note 2 to entry: its upper limit is called the “top of the aquifer” and its base is called the “bottom of the aquifer”
3.2
aquitard
body of rock or stratum of sediment that restricts but does not prevent the flow of groundwater from one
aquifer to another
3.3
backfill
material used for refilling any borehole or trench, except groundwater
3.4
borehole heat exchanger
BHE
consists of vertical or inclined boreholes with a loop, to circulate a heat transfer fluid and a borehole
backfill
3.5
borehole heat exchanger field
BHE field
area with several BHEs that are connected in the same hydraulic circulation system
3.6
borehole heat exchanger loop
BHE loop
pipe system in the borehole, which contains the fluid for heat transfer
8
---------------------- Page: 10 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
3.7
borehole heat exchanger system
BHE system
the BHE system consists in four subsystems (Figure 1):
1) borehole heat exchanger;
2) horizontal piping;
3) manifold;
4) thermal plant (technical room) with all installation except heat pump
Note 1 to entry: the borehole heat exchanger system is considered as a unit including the entire borehole heat
exchanger field
3.8
effective borehole thermal resistance
effective thermal resistance between the mean temperature at the wall of the borehole and the mean fluid
temperature for thermally quasi-steady-state conditions in the borehole
Note 1 to entry: “borehole thermal resistance” always refers to the effective borehole thermal resistance
3.9
effective thermal conductivity
thermal conductivity determined by a thermal response test as effective value over the entire length of
the borehole heat exchanger
Note 1 to entry: implicit allowance also is made for unrecognized influencing factors, e.g. groundwater flow, as
long as the heat transport can still be regarded as heat conduction
3.10
fluid return
flow from the BHE
3.11
fluid supply
flow to the BHE
3.12
g-functions
the G-functions are dimensionless functions describing the relation between temperature change, load
and time for a specific BHE configuration, derived from more complex numerical or analytical solutions
3.13
ground source heat pump system with BHE
BHE GSHPS
BHE system including the horizontal piping, manifolds, the heat pump and circulation pump
3.14
grout
backfilling material for sealing of boreholes composed of clay and/or cement and additional components
(rock powder, etc.). Solid materials especially in case of cementous grouts shall be mixed with water
forming a pumpable slurry
9
---------------------- Page: 11 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
3.15
heat transfer fluid
HTF
liquid fluid circulated through the BHE loop for the heat transport
3.16
injection pipe
tremie pipe or permanent grout injection pipe
3.17
shank spacing
distance between the centres of the U-pipes
3.18
slurry
liquid grout mixture at the time of mixing
3.19
thermal plant
heating/ including the heat pump installation
3.20
tremie pipe
grout injection pipe
3.21
COP
Coefficient Of Performance
ratio of the useful heating power to the electric power of a heat pump
3.22
EER
Energy Efficiency Ratio
ratio of the useful cooling power to the electric power of a chiller
4 Geological and environmental aspects
4.1 General
The designer shall check whether the location of the planned installation is situated in any areas defined
in spatial planning documents. These could be areas of special protection of natural resources (water
protection, nature protection) or areas of specific risks (endangered areas, landslides, contaminated sites,
etc.).
It shall be checked whether there are hydrogeological conditions (artesian aquifers, shallow groundwater
table, perched groundwater, etc.) that could require special consideration or even impact or risk
assessments.
The designer shall assess whether the available geological and hydrogeological information is sufficient
for the project in question.
10
---------------------- Page: 12 ----------------------
SIST EN 17522:2023
EN 17522:2023 (E)
4.2 Geological and hydrogeological risks
4.2.1 Artesian aquifers
When the drilling penetrates an artesian aquifer, the groundwater level rises above ground level and can
overflow uncontrollably at the wellhead. The use of improper drilling techniques or equipment selection
can result in uncontrolled upwelling and pressure loss. This represents the main risks when artesian
aquifers are penetrated.
Drilling in the artesian aquifer is a risk. Special specifications regarding drilling methods and BHE
...
SLOVENSKI STANDARD
oSIST prEN 17522:2020
01-julij-2020
Konstruiranje in izdelava vrtinskih toplotnih izmenjevalnikov
Design and construction of borehole heat exchangers
Planung und Bau von Erdwärmesonden
Ta slovenski standard je istoveten z: prEN 17522
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
oSIST prEN 17522:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN 17522:2020
---------------------- Page: 2 ----------------------
oSIST prEN 17522:2020
DRAFT
EUROPEAN STANDARD
prEN 17522
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2020
ICS 07.060
English Version
Design and construction of borehole heat exchangers
Planung und Bau von Erdwärmesonden
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 451.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17522:2020 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
Contents Page
European foreword . 4
4.1 General. 7
4.2 Geological and hydrogeological risks . 7
4.2.1 Artesian aquifers . 7
4.2.2 Stacked aquifers with different groundwater potential . 7
4.2.3 Groundwater and soil chemistry . 8
4.2.4 Gas occurrence . 8
4.2.5 Ground stability . 8
4.2.6 Swelling and shrinking minerals or soils . 8
4.2.7 Contrasting geological sequence (Alternated bedding) . 8
4.2.8 Karst geology . 9
4.2.9 Frost susceptibility . 9
4.2.10 Groundwater protection area . 9
4.3 Anthropogenic risks . 9
4.4 Environmental aspects . 10
4.4.1 Influence on groundwater . 10
4.4.2 Environmental Impact Due to Construction Works . 10
5.1 General. 11
5.2 Borehole heat exchanger . 12
5.3 Horizontal piping . 13
5.4 Manifolds . 13
5.5 Thermal plant . 14
6.1 General. 14
6.2 General Properties . 14
6.2.1 General. 14
6.2.2 Plastic materials . 15
6.2.3 Connection methods . 16
6.2.4 Metallic materials . 17
6.2.5 Heat transfer fluid . 17
6.2.6 Backfilling material . 18
6.3 Component selection criteria . 19
6.3.1 General. 19
6.3.2 BHE loops . 19
6.3.3 Horizontal pipes . 19
6.3.4 Manifolds . 20
6.3.5 Heat transfer fluid . 20
7.1 Steps of Design . 20
7.2 Sizing . 21
7.2.1 General. 21
7.2.2 General methodology . 22
7.2.3 Thermal properties of the ground . 24
7.2.4 Thermal Response Test (TRT) . 25
7.2.5 Calculation procedure . 31
7.2.6 Simulation . 32
7.2.7 Hydraulic design . 33
8.1 General. 34
8.2 Site Preparation and planning . 34
8.3 Drilling . 34
2
---------------------- Page: 4 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
8.3.1 General . 34
8.3.2 Drilling diameter . 35
8.3.3 Drilling fluid . 35
8.3.4 Monitoring and Documentation of the Drilling Process . 35
8.3.5 Backfilling. 35
8.4 Borehole Heat Exchanger Loop . 36
8.5 Borehole Heat Exchanger Loop Installation . 36
8.6 Backfilling and Grouting procedure . 37
8.6.1 General . 37
8.6.2 Grouting procedure . 37
8.6.3 Other backfilling procedure . 37
8.7 Horizontal Piping . 38
8.8 Testing of BHE – Leakage Check, Flow Check, Grouting Check, Geophysical
Measurements . 38
8.9 Manifolds . 39
9.1 General . 39
9.2 Heat transfer fluid . 40
9.3 Filling of the System . 40
9.4 Drying of New Buildings . 40
9.5 Commissioning . 40
9.6 Documentation . 40
10.1 Operation . 40
10.2 Monitoring. 41
10.2.1 General . 41
10.2.2 Temperature . 41
10.2.3 Pressure . 42
10.2.4 Flow rate . 42
10.3 Maintenance . 42
12.1 General . 43
12.2 Heat carrier fluid . 43
12.3 Borehole heat exchangers . 43
12.3.1 Backfilled boreholes . 43
12.3.2 Water filled boreholes . 43
12.4 Horizontal pipes . 44
12.5 Documentation . 44
Annex A (informative) Insulation of horizontal piping. 45
Annex B (informative) Example simulation time . 46
Annex C (informative) Commissioning Checklist . 49
Annex D (informative) Examples of thermal conductivity and volumetric - heat capacity of
the underground . 51
Bibliography . 53
3
---------------------- Page: 5 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
European foreword
This document (prEN 17522:2020) has been prepared by Technical Committee CEN/TC 451 “Water
wells and borehole heat exchangers”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
4
---------------------- Page: 6 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
1 Scope
This document covers standardization in the field of geological and environmental aspects, design,
drilling, construction, completion, operation, monitoring, maintenance, rehabilitation and
decommissioning of borehole heat exchangers for uses of geothermal energy.
The direct expansion and thermal syphon techniques are excluded from this document
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12201-1:2011, Plastics piping systems for water supply, and for drainage and sewerage under
pressure - Polyethylene (PE) - Part 1: General
EN 12201-2:2011, Plastics piping systems for water supply, and for drainage and sewerage under
pressure - Polyethylene (PE) - Part 2: Pipes
EN 12201-3:2011, Plastics piping systems for water supply, and for drainage and sewerage under
pressure - Polyethylene (PE) - Part 3: Fittings
EN 12201-5:2011, Plastics piping systems for water supply, and for drainage and sewerage under
pressure - Polyethylene (PE) - Part 5: Fitness for purpose of the system
EN ISO 15875-1:2003, Plastics piping systems for hot and cold water installations - Crosslinked
polyethylene (PE-X) - Part 1: General (ISO 15875-1:2003)
EN ISO 15494, Plastics piping systems for industrial applications - Polybutene (PB), polyethylene (PE),
polyethylene of raised temperature resistance (PE-RT), crosslinked polyethylene (PE-X), polypropylene
(PP) - Metric series for specifications for components and the system (ISO 15494:2015)
EN ISO 22391-1, Plastics piping systems for hot and cold water installations - Polyethylene of raised
temperature resistance (PE-RT) - Part 1: General (ISO 22391-1:2009)
EN 1057, Copper and copper alloys - Seamless, round copper tubes for water and gas in sanitary and
heating applications
EN 12449, Copper and copper alloys - Seamless, round tubes for general purposes
EN 1965-2, Structural adhesives - Corrosion - Part 2: Determination and classification of corrosion to a
brass substrate
EN 12168, Copper and copper alloys - Hollow rod for free machining purposes
EN ISO 1127, Stainless steel tubes - Dimensions, tolerances and conventional masses per unit length (ISO
1127:1992)
EN 10216-5, Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 5: Stainless
steel tubes
5
---------------------- Page: 7 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
aquifer
underground geological formations containing water that can be partially mobilised by gravity and
which of permeable and/or cracked or fractured rocks that allow enough transmission of groundwater
to create a significant flow and catchment of a significant amount of water
Note 1 to entry: An aquifer can be fully or partly saturated.
Note 2 to entry: Its upper limit is called the “top of the aquifer” and its base is called the “bottom of the aquifer”
3.2
aquitard
body of rock or stratum of sediment that retards but does not prevent the flow of groundwater from
one aquifer to another
3.3
borehole heat exchanger
BHE
consists of the borehole with a loop, to circulate a heat transfer fluid, and a borehole filling
3.4
BHE loop
part of the pipe system in the borehole, which contains the fluid for heat transfer
3.5
heat transfer fluid
HTF
fluid circulated through the BHE for the heat transport
3.6
BHE system
one or more BHE connected in one hydraulic circulation system
Note 1 to entry: It does not include the heat pump or circulation pump
3.7
ground source heat pump system
GSHPS
BHE system including the horizontal piping, manifolds, the heat pump and circulation pump
3.8
BHE field
area with several BHEs systems that are not connected in the same hydraulic circulation system
6
---------------------- Page: 8 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
3.9
backfill
material used for refilling any borehole or trench
3.10
grout
backfilling material composed of cement and water mixture and other additional components (clay
minerals, etc.)
3.11
fluid
gas, vapour, liquid or combinations thereof
4 Geological and Environmental aspects
4.1 General
The design shall check whether the location of the planned installation is situated in any areas defined
in spatial planning documents. These could be areas of special protection of natural resources (water
protection, nature protection) or areas of specific risks (endangered areas, landslides, contaminated
sites, etc.).
If the installation would be situated on such protected areas, it shall be verified that the design is in
accordance with the specific geological conditions.
It shall be checked whether there are hydrogeological conditions (artesian aquifers, shallow
groundwater table, perched groundwater, etc.) that could require special consideration or even impact
or risk assessments.
The designer shall assess whether the available geological and hydrogeological information is sufficient
for the project in question.
4.2 Geological and hydrogeological risks
4.2.1 Artesian aquifers
When the drilling penetrates into an artesian aquifer, the groundwater level rises over the orifice of the
borehole. Uncontrolled upwelling and pressure loss would occur from use of improper drilling
techniques or equipment selection. In certain cases, the upwelling (into shallower aquifers) might not
be directly evident. This represents the main risks when artesian aquifer is penetrated.
Drilling in the artesian aquifer is a risk. Special specifications regarding drilling methods and BHE
construction shall be implemented.
4.2.2 Stacked aquifers with different groundwater potential
Drilling through sealing layers between aquifers could result in leakage from one aquifer to another and
result in impact on chemical characteristics of groundwater or hydraulic conditions. This could also
cause an undesired drop or increase of groundwater level in one or more aquifers. Consequences could
be decreased productivity of water sources or deteriorated formation conditions.
Groundwater flow conditions and qualities can also be affected adversely where drilling penetrates two
or more groundwater layers. In this case, the possibility of uncontrolled water exchange between the
individual aquifers via the borehole needs to be taken into account. A hydraulic short circuit should be
avoided for groundwater protection reasons, especially where one of the penetrated layers contains
highly mineralized or contaminated groundwater.
If drilling would cross through several aquifers, at least the aquitards shall be sealed.
7
---------------------- Page: 9 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
4.2.3 Groundwater and soil chemistry
The chemical composition of the groundwater (high sulphate concentration, high salinity, etc.) could
adversely affect the sealing properties and stability of the backfilling.
Drilling or excavating near mineral water springs or wells could adversely affect the mineralogical
composition of groundwater.
4.2.4 Gas occurrence
Under certain geological conditions, gas of geogenic origin can accumulate in cavities and trap
structures in the subsurface. When drilling in these areas, the gas could leak uncontrollably through the
borehole and pose a safety risk (toxic or explosive gases) or an environmental risk (greenhouse gases).
Gas deposits could occur in areas with volcanic activity or above geological layers containing coal, peat,
hydrocarbons, sulphides, etc. If the risk of drilling gas at the project site is known or can be predicted
based on geological research, certain safety measures (e.g. explosion protection concept, special backfill
material) are required or the drilling depth shall be limited or the drilling shall be terminated.
4.2.5 Ground stability
Unstable ground could be found especially in the following geological situations:
— intensively fissured, faulted and breccia zones, provoking formation of natural or anthropogenic
cavities;
— soft fragile rocks representing unstable ground (e.g. volcanic or sedimentary rocks).
4.2.6 Swelling and shrinking minerals or soils
Presence of evaporates or swelling clays presents a risk of subsidence or swelling in the case of
connection of shallow or deep aquifers with evaporitic or clay layers because of unsuitable or hardly
feasible underground operations.
4.2.7 Contrasting geological sequence (Alternated bedding)
Geology is highly diverse, and could range from structures represented by unconsolidated sand, clay
and gravel going to very complex situations including unconsolidated or consolidated sedimentary
(sandstone, limestone – fissured and frequently karstified) or crystalline (metamorphic and igneous)
rocks. An adequate knowledge of the geological conditions and associated hydrodynamic properties of
the selected site represents the base for any BHE drilling project. Adequate prior analysis of site
conditions raises the probability of an efficient and long-lasting product; this also contributes to the
management and protection of groundwater resources (quantity and quality) to be exploited through
future projects (e.g. water wells of different purposes and configurations).
The lithological description of the geological sequence be drilled and the structural characterization of
the site area are both compulsory in order to provide sufficient information for the preparation of a
BHE design and provision of adequate drilling machineries and auxiliary equipment for efficient
construction works; whilst avoiding, minimizing and/or controlling the potential geologic risks during
drilling.
Depending on the complexity of the project and of the geological conditions, the standard set of topics
to be described should refer to the following aspects (if appropriate):
— occurrence and description of the regional geologic structure(s) - sedimentary basin, folded
structures and/or faults;
— the lithological (specific) description (from bottom to top or reverse) of the litho-stratigraphic units
(formations, beds, layers, or horizons) to be drilled;
8
---------------------- Page: 10 ----------------------
oSIST prEN 17522:2020
prEN 17522:2020 (E)
— occurrence and characterization of local tectonic (structural) discontinuities – faults, fissures,
fractures (particularly in case of hard rocks);
— occurrence and characterization of dissolution voids and channels (in case of carbonate and
evaporite rocks);
— hydrological aspects (groundwater chemistry, redox potential, depth of sweet/salt level, level of
phreatic groundwater, regional groundwater flow for every aquifer, hydraulic conductivity,
porosity / thermal parameters);
— inventory of other users in the vicinity (groundwater extraction wells, groundwater energy wells,
borehole heat exchangers).
4.2.8 Karst geology
Karstified zones can represent strong heterogeneity of the ground and risk of caverns. High probability
of occurrence of caverns leads to several risks: collapsing of borehole, subsidence of the ground, losses
of drilling fluids, problems with backfilling, turbidity and solids in groundwater, unstable temperature
of groundwater (too low in winter, too high in summer), hardly predictable, unreliable modelling.
Geological and hydrogeological conditions in the depth of karst area are often not sufficiently known to
make a reliable prediction without additional investigation.
4.2.9 Frost susceptibility
Because the temperature of the fluid in the BHE can be below 0 °C, there could be a risk of freezing the
soil causing upheaval of the horizontal part and affect the sealing properties of the borehole filling an
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.