Ocean System Ltd and Another v. Mtr Corporation Ltd and Another

HCA 1283/2023

[2026] HKCFI 5668

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

ACTION NO 1283 OF 2023

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BETWEEN

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DECISION

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1.Introduction

1.1  This action concerns allegations of noise and vibration affecting Units 608 and 609 (“Subject Office”), 6^th Floor, Tower 1, Admiralty Centre (“Subject Building”).  The 1^st Plaintiff (“P1”) and the 2^nd Plaintiff (“P2” and collectively “Ps”) are respectively the registered owner and tenant of the Subject Office.  P2 is a firm of solicitors, and one of the partners, Ms Corrina Kwan (“Ms Kwan) is a director of P1.

1.2  The 1^st Defendant (“D1”) is the manager of the Subject Building.  The 2^nd Defendant (“D2” and together with D1 collectively “Ds”) was at all material times the contractor appointed by D1 responsible for the heating, ventilation and air-conditioning system (“HVAC System”) of the Subject Building.  Since the expiration of its contract with D1 in November 2025, Young’s Engineering Co Ltd has assumed the role previously undertaken by D2.

1.3  The Subject Building consists of a 4-storey podium providing shopping and restaurant facilities (“Shopping Centre”) and two towers, with approximately 292 owners and tenants.  On the 4^th Floor of the Subject Building is a plant room (“Plant Room”) which houses multiple chiller plants (“Chillers”), water pumps (“Pumps”) and piping networks of the HVAC System.

1.4  It is Ps’ case that since October 2022, loud “Bong” noises and strong vibrations have affected the Subject Office multiple times per day, and it is said that such alleged nuisance (“Alleged Nuisance”) is attributable to the HVAC System.  Ps’ claims against Ds are variously advanced on the bases of breach of duties (including statutory duties) and breach of the Deed of Mutual Covenant (“DMC”).  For reasons which will become apparent below, it is pertinent to note at the outset that Ps initially identified the Chillers and Pumps as the main culprits for the Alleged Nuisance (“Original Cause”) but have since shifted their focus to the opening and closure of the valves in the piping of the HVAC System (“Additional Cause”).

1.5  At the Initial Case Management Conference held pursuant to Practice Direction 5.7 on 2 March 2026 (“ICMC”), I directed that the following two applications be heard together:

(1)  Paragraph 4 of the 1^st Defendant’s summons dated 12 May 2025 (“CMC Summons”) for an order for joint inspection which entails simultaneous acoustic and vibration measurement at the Subject Office and the Plant Room to be conducted by the acoustic and engineering experts of the parties on terms set out therein (“Inspection Application”);

(2)  Ps’ summons dated 14 October 2025 against Ds for specific discovery of the classes of documents enumerated in Schedules I and II thereto (“Discovery Application”).

1.6  The Discovery Application in its original scope sought around 70 classes (including subclasses) of documents (“Original Scope”).  Under the terms of RHC Order 24, rule 8, on the hearing of an application for specific discovery under RHC Order 24, rule 7, if the court is satisfied that discovery is not necessary at a certain stage of the cause or matter, the court may dismiss or adjourn the application and shall in any case refuse to make an order if and so far as it is of the opinion that the discovery is not necessary either for disposing fairly of the cause or matter or for saving costs.  At the ICMC, I had indicated that there was ample room for Ps to curtail the scope of the Discovery Application.  By a letter dated 5 March 2026 (“5/3/26 Letter”), Ps curtailed the scope of the Discovery Application to 18 classes of documents (“Curtailed Scope”).  As will be seen below, at the substantive hearing, the scope of the Discovery Application was further reduced to only 3 classes of documents (“Pursued Scope”).

1.7  At the substantive hearing of the two applications, Ps were represented by Mr William Wong SC (leading Mr Jonathan Chan), D1 by Ms Audrey Eu SC (leading Mr Albert Chan) and D2 by Mr Solomon Lam.

2.The interplay between the two applications

2.1  Despite having first occurred in October 2022, the parties remain in dispute as to the cause of the Alleged Nuisance.  At the invitation of Mr Wong, I have viewed the video clips in evidence adduced by Ps.  It seems to me quite plain that, even as recently as on 19 and 23 May 2026, the Subject Office was subject to sudden thumping noises.

2.2  On the present evidence, it seems to me that the frustration identified in Ms Kwan’s evidence is legitimate, especially when the Alleged Nuisance has remained for an extended period of time.  Whilst I can understand Ps’ frustration, I have also taken into account Ms Eu’s submissions (which are not disputed by Mr Wong) that there is a degree of distrust between Ps and D1, in particular when it is Ps’ case that they were initially misdirected by D1 as to the cause of the Alleged Nuisance.  The current state of play identified by counsel is as follows:

(1)  On Ms Eu’s part, she points out that despite these proceedings having been commenced in August 2023, the pleadings were only closed in August 2025.  Ps have already prepared and filed 9 expert reports, and she says that the disproportionality and lack of progress is obvious and such were the reasons why this led to the assignment of a trial judge for these proceedings (§1.5 above);

(2)  Ms Eu further points out that the Inspection Application is crucial, as D1 has thus far not been afforded access to the Subject Office to carry out a systematic investigation to verify either the existence or the extent of the Alleged Nuisance.  Moreover, she reminds the court that 30,000 pages of documents have already been disclosed and contends that it is plain that the Discovery Application has not been sensibly controlled, as evidenced by the drastic reduction in its scope from the Original Scope to the Curtailed Scope and finally the Pursued Scope;

(3)  Conversely, Mr Wong says that the two applications must be viewed in the context that it was only with the assistance of their experts that Ps have identified the Additional Cause, which, even on Ms Eu’s submissions, was only done in October 2025, and the identification of the Additional Cause had been delayed by D1’s misdirection of Ps to the Original Cause and withholding of information.

2.3  I have taken into account the above broad context.  In my view, it is unnecessary to dwell on them given the sensible position advanced by Mr Wong at the hearing.  The key consideration is that these proceedings should be constructively (and fairly) advanced.

2.4  At the outset of the hearing, Mr Wong very fairly confirmed that (1) Ps do not oppose a joint inspection in principle and (2) the proper context of the Discovery Application is that the discovery sought is not for the purpose of preparing witness statement or expert evidence but primarily for the purposes of (a) ensuring that any joint inspection is fruitful and (b) enabling Ps to participate on an equally-informed basis.  

2.5  For the purpose of the proposed joint inspection, D1 has on 4 March 2025 proposed a method statement (“D1 Method Statement”).  Under the terms of CMC Summons §4, the proposed joint inspection is to be held subject to a number of directions having been complied with, namely: (1) for Ps and D2 to comment on the D1 Method Statement, (2) for a without prejudice meeting between the parties’ experts to discuss and agree upon a method statement and (3) for a mechanism for the parties to seek further directions from the court should their experts fail to agree on a method statement.

2.6  The following matters are plain from the D1 Method Statement:

(1)  The exercise identified therein is essentially a factual one, in that noise and vibration monitoring is proposed to be carried out at the Plant Room and the Subject Office for 5 working days (or a longer duration if agreed) to capture noise and vibration measurement data for comparison.  Essentially, it is an exercise of data capturing to see if there are any correlations between the data captured in the Plant Room on the one hand and the Subject Office on the other;

(2)  The focus is on the Chillers and Pumps (ie the Original Cause) since the locations at which monitoring equipment proposed to be placed in the Plant Room are near or close to the Chillers and Pumps (§5.4.1 thereof).

2.7  As noted at §1.4 above, Ps had initially identified the Chillers and Pumps as the main culprits for the noise and vibration (ie Original Cause).  However, Ps have since shifted their focus to the Additional Cause.

2.8  As the shift postdates the D1 Method Statement, Mr Wong says that additional discovery is required to enable Ps to propose a method which also captures monitoring at valve locations, without which the current proposed joint inspection is unlikely to identify comprehensively the source of the Alleged Nuisance and is likely to result in an incomplete and futile investigation.

2.9  Ms Eu contends that the joint inspection should proceed in accordance with the D1 Method Statement.  She says that, whilst Ps have shifted their focus to the Additional Cause, they are still maintaining that the Original Cause is a possible cause of the Alleged Nuisance.  As such, even if only by the process of elimination (ie eliminating the Original Cause as a cause for the Alleged Nuisance), the proposed joint inspection will nevertheless serve to narrow the issues between the parties.

2.10  In order to understand the issues debated between counsel, it is necessary to provide a brief outline of the HVAC System and how it operates.  It is pertinent to note that the evidence of the parties on the foregoing is conflicting, but for the purpose of these applications, it is neither necessary (nor indeed appropriate) to resolve such conflicts.

3.The HVAC System

3.1  Ps have engaged Mr Patrick Wong (“Ir Wong”), a registered engineer, and Mr K K Kwok, an acoustic expert (collectively “Ps’ Experts”).  According to Ir Wong, by reference to a plan disclosed by D2, the HVAC System comprises various distinct piping systems: (1) Condensing Water Pump (“CNP”) Piping System, (2) Primary Chiller Water Pump (“PCP”) Piping System, (3) Secondary Chilled Water Pump (“SCP”) Piping System and (4) Seawater (Transfer) Piping System.  The D1 Method Statement proposes that the measuring equipment is to be placed at locations near the Chillers, CNPs, PCPs and SCPs in the Plant Room (as identified therein).

3.2  According to D1’s evidence:

(1)  A simple explanation of the HVAC System in the Subject Building is that chilled water is supplied via pipes into the coils of the Fan Coil Units (“FCUs”), and when air passes across the cold coils of the FCUs, the air is chilled.  The supply of air-conditioning in the Subject Building can therefore be controlled by the chilled water (and in particular, by the opening and closing of the valves in the pipes).  In the Subject Building, apart from special requests for additional air-conditioning made by owners and/or tenants, the air-conditioning is generally supplied to (1) the offices from 8 am to 6 pm on weekdays and 8 am to 1 pm on Saturdays and (2) the Shopping Centre from 8 am to 8 pm every day.  As such, generally the valves open and close once per day at around the aforesaid times[1];

(2)  More specifically[2], chilled water in the HVAC System originates from the machinery in the Plant Room and is then distributed to each floor through risers.  At each floor (inside the risers located in the air-conditioning room of each floor), there is a “T valve” which control the supply of chilled water to the branches of chilled water pipes of each floor.  The T valves are kept open all the time except for ad hoc incidents, for example where there is a need for air-conditioning works to be carried out.  After passing the T valve of a floor, the chilled water in the HVAC System would then be distributed to different parts of that floor (ie zones) through the chilled water pipes of that floor.  Each zone usually only has one valve and the zone valves control the supply of chilled water to the chilled water pipes of that zone.  The zone valves can only be open/closed and the water flow cannot be modulated.  After passing the zone valves, the chilled water then eventually enters the FCUs in a unit;

(3)  The Subject Office is located in Zone 5 and Zone 6 of 6/F and the BMS (Building Management Service) records which have already been disclosed show that the opening and closure of the Zone 5 valve and the Zone 6 valve on the 6/F follow the pattern set out at subparagraph (1) above[3];

(4)  As to how the HVAC System is operated[4], the majority of the HVAC equipment in the Plant Room is operated manually and factors such as heat load requirement, ambient temperature, day and time of the day, and needs and demands by the tenants of the Subject Building are some of the major factors considered when deciding upon the number and combination of machines to be operated in the Plant Room.  There can be over 1,000 different combinations as to which and how many chillers or pumps are operated.  Annex A of Chau 5^th contains a document titled “General Notes for Chiller Plant Operation” and sets out the recommended operation matrix against various outdoor temperatures and time periods, targeted temperature difference between chilled water supply and return and on-site practice (“General Notes”);

(5)  D1’s evidence is that not all valves are connected to the BMS.

3.3  The overarching point made by Ms Eu is that, as evidenced by the BMS records of the Zone 5 and Zone 6 valves on 6/F, the opening and closure of valves, ie the Additional Cause, do not take place repeatedly throughout the day.  The Additional Cause therefore cannot be the source of the Alleged Nuisance in the Subject Office which, on Ps’ case, occur around 10 times a day.

3.4  Conversely, according to Ps’ Experts:

(1)  The term “zone valve” is a generic description of a valve which distributes chilled water to a zone, ie a large area, for example, certain floors of a commercial building or a shopping centre.  Common categorization has always named the valve to distribute chilled water to (a) the pipe extended from the Plant Room as “Zone Valve” (eg riser), (b) the further divided branches to each floor as the “Subsidiary Zone Valve” and (c) to the individual units the solenoid On/Off valve (“Solenoid Valve”)[5];

(2)  There is therefore an apparent disparity in how the term “Zone Valve” is used in the parties’ respective evidence.  I adopt the terminology used by Ps’ Experts;

(3)  As I understand the evidence of Ps’ Experts, the BMS records referred to at §3.2(3) above are the records of, using their terminology, the Subsidiary Zone Valves of Zone 5 and Zone 6 on 6/F.  They dispute D1’s evidence that the Zone Valves (ie the riser or the T valves) are not monitored by the BMS and therefore have no BMS records, as it is illogical when the Subsidiary Zone Valves are so monitored[6];

(4)  Zone Valves are built within the SCP piping system and it is a closed loop design.  Whilst accepting that the disclosed BMS records of the Subsidiary Zone Valves of Zone 5 and Zone 6 on 6/F opened and closed once daily, the Zone Valves (which I understand to also include the Subsidiary Zone Valves) of, for example, the Shopping Centre would open and close frequently and irregularly, for, they opine, the demand for the chilled water flow for restaurants or shops needs to be more frequently adjusted due to changing demands of these commercial establishments during day and night.  They take the view that even if other valves do not serve the Subject Office directly, the operation of those valves could create noise and vibration in the same SCP loop to affect the Subject Office[7]. In other words, there is a dispute between Ps and D1 as to, amongst other things, the frequency of the opening/closure of certain valves (especially those serving the Shopping Centre);

(5)  As to the cause of the Alleged Nuisance, Ps’ Experts opine as follows:

(i)  the Alleged Nuisance is not attributable to a single source or a single location (or only the Original Cause).  Rather, the Subject Office has been affected by the operation of valves at different locations within the piping systems, with noise and vibration transmitted to the Subject Office from different parts of the HVAC System multiple times each day.  The cause is therefore structural and involves different combinations of HVAC components[8];

(ii)  The Alleged Nuisance during business hours (often more than 10 times a day) is caused mainly due to the opening and closure of the valves (likely to be Zone Valves (which I understand to include Subsidiary Zone Valves) which distribute chilled water to different zones including the Shopping Centre).  These valves could be built inside or outside the Plant Room as they distribute chilled water to different areas or zones. Usually, except for the need to turn on additional SCP, the operation of the valves which caused the Alleged Nuisance to the Subject Office during business hours should have nothing to do with the Original Cause[9];

(iii)  The Alleged Nuisance is caused not only by one source or one location.  The Subject Office has been affected by operation of different valves at different locations within the piping system (and not confined to the Plant Room).  CCTV shows that the Alleged Nuisance is of different loudness - some seemed very close and some seemed from farther away.  The problem is therefore structural[10].

3.5  At the hearing, Mr Wong has confined the scope of the Discovery Application to the following three classes of documents (ie the Pursued Scope):

(1)  The updated plans, or any plan, drawing or document, showing the current locations of the valves on each floor of the Shopping Centre, 4/F, 5/F and 6/F (“Class 1”);

(2)  The up-to-date and/or existing Operating and Maintenance Manuals of all machinery and equipment comprising the HVAC System (“Class 2”);

(3)  The BMS records from 21 August 2025 to date in respect of all plant, equipment and valves of the HVAC System which are (i) located on each floor of the Shopping Centre, 4/F, 5/F and 6/F and (ii) connected to the BMS (“Class 3”).

3.6  I shall explain below how the Pursued Scope differs from the Curtailed Scope and its implications.  For present purpose, suffice it to note Mr Wong says that the Pursued Scope is necessary for a meaningful joint inspection to be carried out in respect of the Additional Cause.  The question for determination is whether (as Ms Eu contends) a joint inspection in accordance with the D1 Method Statement should proceed irrespective of the outcome of the Discovery Application, or (as Mr Wong argues) whether a joint inspection should, if Ps prevail in the Pursued Scope (or any part thereof), await such disclosure such that a more comprehensive joint inspection can be agreed between the experts.

4.The Inspection Application

4.1  D2 does not oppose the Inspection Application and intends to participate through its own acoustic and engineering experts.  Ps do not oppose inspection or expert investigation as a matter of principle subject to a number of caveats.  Given the foregoing, it is unnecessary to set out the applicable principles at length. 

4.2  The Inspection Application is made pursuant to RHC Order 29, rules 2 and 3.  The guiding principle in the context of an entry and test application is “whether it is reasonable or necessary for promoting a fair and satisfactory trial to have the test in question conducted”: Li Ching Har v Wong Suk Kit [2018] 2 HKLRD 806 at §§19-20.  For the following reasons, I am of the view that the proposed joint inspection should proceed in accordance with the D1 Method Statement, without awaiting the further documents to be disclosed under the Discovery Application

4.3  A number of reservations are raised by Mr Wong. 

4.4  First, given that the Additional Cause is now Ps’ focus, any joint inspection directed at only the Original Cause is incomplete and likely of limited utility.

4.5  I do not accept the above submission.  Even if the joint investigation only focusses on the Original Cause, I am not persuaded that this deprives it of its forensic value.  Ps’ pleaded case continues to allege that the Original Cause is a possible cause of the Alleged Nuisance. Although Ps have since placed greater emphasis on the Additional Cause, they have not abandoned the Original Cause.  In those circumstances, an investigation directed at the Original Cause serves a legitimate forensic purpose irrespective of Ps’ more recent emphasis on valves and associated pipework.  If the investigation ultimately reveals no meaningful correlation between the noise and vibration detected in the areas near the Chillers and Pumps on the one hand and the Subject Office on the other, that result is valuable in and of itself, as the Original Cause may thereby be excluded as a potential source of the Alleged Nuisance, narrowing the issues requiring determination at trial.  To be fair, I do not believe Mr Wong seriously disputes the foregoing to be the case.

4.6  Secondly and relatedly, Ps contend that any present-day investigation of the Chillers and Pumps may be of limited or misleading value because substantial repairs, modifications and maintenance works have been undertaken to those items since the complaints first arose.  In my view, whether, and if so to what extent, those matters affect the weight to be attached to the investigation results can ultimately be assessed in light of the evidence as a whole.

4.7  Thirdly, section 5.1 of the D1 Method Statement proposes that, during the joint inspection, the machinery in the Plant Room will be operated following “usual operation conditions determined by [D2]”.  Mr Wong argues that (1) there is a risk that the proposed investigation may not be conducted under conditions that appropriately reflect the matters in dispute and (2) it is inherently unfair that the testing conditions are fixed unilaterally without any meaningful input from Ps’ Experts, especially when Ps do not have any means to verify what are the usual operation conditions. 

4.8  I am not persuaded that the above concerns are a weighty consideration, if those concerns are understood as an allegation that the operation conditions during the proposed joint inspection will be manipulated so as  not to reflect the “usual” operation conditions and thereby create a scenario favourable to D1 and D2.  One must bear in mind that the proposed joint inspection is only focused on the Plant Room, and in particular on the Chillers and Pumps.  D1 has already disclosed BMS records of the equipment in the Plant Room together with the Subsidiary Zone Valves of Zone 5 and Zone 6 on 6/F for the period from 17 September 2022 to 2 February 2025 (“Disclosed BMS Records”), and one would expect that the “usual” operations in terms of the level of activities can be identified from the records already disclosed.  I have no doubt that Ps’ Experts will keep a log of the operations during the proposed joint inspection, and any abnormally low level of activity (if any) can be identified.  It seems to me that the above concerns are in all likelihood generated by Ps’ mistrust of D1, but I have to proceed on the basis that the joint inspection will be conducted in good faith.  In any event, as I have pointed out, Ps already have in their possession a set of data to enable them to identify any manipulation.  For example, if Chiller X and Zone Valve Y are shown in the Disclosed BMS Records to have a certain degree of activity, then if they are operated during the proposed joint inspection in such reduced level of activity which is not consistent with the Disclosed BMS Records, such anomaly may be identified.

4.9  Fourthly, and relatedly, Mr Wong has expressed Ps’ concerns that a separate and later joint inspection in relation to valves will create unfairness.  Ps are concerned that if the joint inspection proposed by D1 proceeds, Ds will then obtain a set of data of noise and vibration recorded at the Subject Office.  The concern is that Ds will then carry out their own investigation based on the data obtained.  If through such investigations, Ds identify the Additional Cause as a cause of the Alleged Nuisance, they will remedy the situation such that any second joint inspection targeting the valves may thereby be rendered contrived.

4.10  As will be seen below, I will accede to Ps’ application for specific discovery of Class 3 which comprises the BMS records of, inter alia, the valves from 21 August 2025 to date.  The significance of 21 August 2025 is that Ps have records of noise and vibration affecting the Subject Office on and after that date with specific timestamps.  The BMS records to be disclosed will enable Ps to identify any correlation between valve activities (and in particular which valve or which potential set of valves) and their own records of noise and vibration.  For example, if the activities of the Zone Valves of the Shopping Centre on 21 August 2025 are identified from the BMS records to be disclosed to correlate with the noise and vibration at the Subject Office, then that should provide a benchmark for further inquiries.  If Ps’ mistrust of D1 turns out to be justified, in that remedial works are surreptitiously carried out after the joint inspection proposed by D1 such that there is no further correlation between the Zone Valves of the Shopping Centre and the noise and vibration at the Subject Office at the second joint inspection, further investigations can be made by Ps as to whether there has been any changes to the Zone Valves of the Shopping Centre since 21 August 2025.  In any event, I repeat my observation above that I have to procced on the basis of a level of good faith between the parties.

4.11  Fifthly, the D1 Method Statement proposes real-time noise (and vibration) measurements inside the Subject Office.  Mr Wong says that Ps have a legitimate concern over confidentiality given that the Subject Office is the office of a firm of solicitors.  As I understand Mr Wong, such risk should be properly addressed and, in any event, minimized (ie by having one instead of two joint inspections).

4.12  As stated in the D1 Method Statement, no audio recordings of sounds will be taken and the testing equipment will solely capture the noise and vibration levels for investigative purposes.  There appears to be no dispute that, whilst the measurement device has a sound recording function, it may be disabled.  Again, the above concern is precipitated by Ps’ mistrust of D1.  I have no doubt that D1 (or D2) has no interest or motive in breaching any confidentiality, and if required, I am prepared to impose an order that Ps be provided with the entirety of the recordings taken during the proposed joint inspection to ensure that the sound recording function is disabled throughout the process.

4.13  Sixthly, it seems to me that a second joint inspection may take some time to arrange, as some of the valves which Ps may wish to monitor may be located within the units of individual owners.  One can imagine that securing consent from the individual owners may take some time.  Even if, under the terms of the DMC, D1 is empowered to enter the individual units to carry out its duties, the coordination involved may still be a significant undertaking.

4.14  For the above reasons, I am of the view that the joint inspection proposed by D1 should proceed.  However, I agree with Mr Wong that the scope should be specified expressly as being limited to an exercise in relation to the Chillers and Pumps and to a limited  factual exercise of identifying any correlation between the data captured in the Plant Room and the Subject Office.  I will therefore amend CMC Summons §4(a) in the following terms:

“There be a simultaneous acoustic and vibration measurement at the Subject Office and the 4/F AC Plant Room ("Inspection") to be conducted by the respective acoustic and engineering experts of the Plaintiffs, the 1st Defendant, and the 2nd Defendant (if any) in accordance with the D1 Method Statement, for the purpose of enabling the parties' respective experts to address the following issues:

(i) Whether the alleged noise and/or vibration complained of by the Plaintiffs exist; and if so, the extent or level.

(ii) Whether the extent or level of the recorded noise and/or vibrations in the Subject Office (if any) exceeds the acceptable level and/or standard to be expected of an office.

(iii)   If the answer to (i) is in the affirmative, whether there exists any causal relationship factual correlation between the recorded noise and/or vibration in the Chillers and Pumps in the 4/F AC Plant Room from the operation of the machinery therein the Chillers and Pumps and the alleged noise and/or vibration on complained of by the Plaintiffs in the Subject Office.”

4.15  I will also make an order in terms of CMC Summons §4(e) for the filing of individual reports but deleting the reference therein to paragraph 4(a)(ii) to correspond to the amendment above.  As this is a predominantly factual exercise, it does not appear to me that a without prejudice meeting and a joint report contemplated under CMC Summons §4(f) are necessary.  I therefore make an order in terms of CMC Summons §§4(a) and (e) as amended.  I also grant liberty to apply.

4.16  The parties are to agree on the timing of the joint inspection and consider whether any order canvassed at §4.12 above should be included.  The parties are to provide an agreed draft order for my approval within 7 days hereof, or, absent agreement, their respective proposed draft order with a 1-page explanation of the disagreement.

5.The Discovery Application

5.1  The principles relevant to an application for specific discovery are trite.

5.2  The jurisdiction to order specific discovery arises where the applicant establishes a prima facie case that: (a) a document, or class of documents, exists or has existed which has not been disclosed; (b) the document is, or has been, in the possession, custody or power of the other party; and (c) the document is relevant to a matter in issue in the action. The burden of establishing those matters rests upon the applicant: Kwok Wai Fung v China Gas Holdings Ltd [2023] HKCFI 83 at §9 and Angela Chen v Wai Wai Chen [2024] HKCFI 962 at §§27, 31.

5.3  Relevance is assessed primarily by reference to the issues arising on the pleadings, considered broadly and realistically.  Discovery is not available for the purpose of a fishing exercise or to pursue matters which, even if established, could not affect the determination of the action: Angela Chen at §§28–30.

5.4  Where discovery is sought by reference to a class of documents, the class must be identified with sufficient precision and must not be framed so broadly as to include documents which are not relevant to the issues in dispute. The order itself must identify the documents or classes of documents required to be disclosed with sufficient certainty: Angela Chen at §§27, 34–36.

5.5  Even where those requirements are satisfied, the Court retains a discretion whether to order discovery. An order will not be made unless the discovery sought is necessary either for disposing fairly of the cause or matter or for saving costs: Order 24 rule 8 RHC; Angela Chen at §27; Kwok Wai Fung at §9. Considerations of proportionality, burden and efficient case management are material to the exercise of that discretion: Angela Chen at §33 and Li Tak Yee Samuel v Société Générale Bank and Trust & Anor, HCA 2478/2009, 16 April 2013 at §§32–34.

5.6  A statement by a party that documents do not exist, or are not within its possession, custody or power, will ordinarily be treated as conclusive at the interlocutory stage unless there is a proper basis for questioning that assertion: Angela Chen at §§27(6) and 40.

5.7  I propose to first deal with Class 3.  In my view, at this stage of the proceedings, only discovery of Class 3 is necessary either for disposing fairly of the cause or matter or for saving costs.

(i)   Class 3

5.8  Class 3 seeks discovery of “the BMS records from 21 August 2025 to date in respect of all plant, equipment and valves of the HVAC System which are: (i) located on each floor of the Shopping Centre, 4/F, 5/F and 6/F; and (ii) connected to the BMS”.

5.9  Class 3 represents a revision of Item 3 of Schedule I.  In its original form, it seeks discovery of “[The BMS records] of all plants and equipment of the HVAC System including all zone valves, the newly installed valves and sensors, as from January 2022 to date.” 

5.10  Class 3 therefore (sensibly) (1) limits the scope to specific floors instead of the entire Subject Building and for a shorter duration, (2) rightly accepts D1’s evidence that the sensors are either not connected to the BMS or not relevant to the Additional Cause and (3) takes into account D1’s evidence that not all valves are connected to the BMS.

5.11  In my view, Class 3 should be further refined to “the BMS records from 21 August 2025 to date in respect of all plant, equipment and valves (limited to the Zone Valves and the Subsidiary Zone Valves)[11] of the HVAC System which are: (i) located on each floor of the Shopping Centre, 4/F, 5/F and 6/F; and (ii) connected to the BMS”.  As noted at 3.4(5) above, Ps’ Experts have not identified the Solenoid Valves as a likely culprit for the Alleged Nuisance.

5.12  There is no dispute that the BMS records exist.  Although the BMS records are maintained by Honeywell Limited (the BMS operator of the Subject Building), they are plainly within the control of D1, as is evidenced by BMS records previously disclosed.  Whilst it is D1’s evidence that the BMS computer system will automatically overwrite itself after a certain time, Ps have curtailed the time period for which discovery is sought.

5.13  I am also satisfied that the limitation to the identified floors is entirely sensible and reasonable.  The Shopping Centre has been identified specifically by Ps’ Experts to be a likely cause and I also take into account Ms Kwan’s evidence that during the closure of McDonalds in the Shopping Centre for renovation, the frequency of the Alleged Nuisance had noticeably reduced.  The 4/F houses the Plant Room.  By reason of the closed-loop feature of the SCP piping system (§3.4(4) above) identified by Ps’ Experts, I am satisfied that the 5/F and the other zones on 6/F are of sufficient proximity.  Of course, Zone 5 and Zone 6 on 6/F are plainly relevant. 

5.14  At present, the Disclosed BMS Records contain only the records in relation to the Subsidiary Zone Valves of Zone 5 and Zone 6 on 6/F.  D1 submits that those records demonstrate that the valves directly serving the Subject Office only open and close at limited frequency and therefore cannot be the cause of the Alleged Nuisance.  According, D1 contends that further disclosure is unnecessary. 

5.15  I am not persuaded by that submission.  The existing disclosure concerns only the Subsidiary Zone Valves of Zone 5 and Zone 6.  Ps’ case, supported by their experts, is that the source of the Alleged Nuisance may lie elsewhere within the HVAC System, including other Zone Valves and Subsidiary Zone Valves which do not directly serve the Subject Office.  Whether D1’s evidence as to the operation of the valves is correct is itself a matter in dispute.  It is precisely those disputes which make the requested records relevant.  The disclosure of the documents covered by Class 3 (as amended) will (1) shed light on the accuracy of D1’s evidence on the pattern of opening and closure of the valves (§3.2(1) above) and (2) enable Ps to identify correlations (if any) with its records of noise and vibration from 21 August 2025 onwards.  In the above regard, I specifically reject Ms Eu’s submission that any further discovery beyond the Disclosed BMS Records amounts to “backward fishing”.

5.16  For the above reasons, I allow Ps’ application for discovery in relation to Class 3 (as amended), but only against D1.  I do not believe Mr Wong has any disagreement with Mr Lam’s submission that the BMS records do not concern D2.

(ii)   Class 2

5.17  Class 2 seeks discovery of “The up-to-date and/or existing Operating and Maintenance Manuals of all machinery and equipment comprising the HVAC System”.  It is a variation of Item 2 of Schedule I which seeks “The updated and completed Operating and Maintenance Manual of the HVAC System”.

5.18  Class 2 therefore seeks to counter the evidence of D1 and D2 that there is no manual for the entire HVAC System as a whole by seeking the manual for the individual machinery and equipment. In relation to D1, Ps point out that it is accepted by D1 that there exist “O&M Manual” of all machinery and equipment.  In relation to D2, Ps point out that D2’s evidence ought not be accepted, as D2 was contractually to produce O&M Manuals which fully describe overall operation of all systems,

5.19  In my view, Ps’ application in relation to Class II can be disposed of on the basis that discovery is not necessary at this stage.  Whilst Ps submit that the manuals are required to enable their experts to understand the operation of the HVAC System and to participate meaningfully in future investigations and expert discussions, I bear in mind that the Additional Cause remains only a hypothesis proffered by Ps’ Experts.  Following the discovery of Class 3, Ps’ Experts will be in a position to identify correlation (if any) between the opening and closure of the Zone Valves and the Subsidiary Zone Valves and the records of the noise and vibration experienced at the Subject Office. 

5.20  If no correlation is identified, it is unclear how Class 2 remains relevant.  Conversely, if a correlation is identified, it does not follow that the disclosure of O&M Manuals of all machinery and equipment comprising the HVAC System becomes necessary.  The Class 3 documents may identity specific valves or combination of valves warranting further investigation.  At the second joint inspection, Ps can simply recreate or simulate the “combination” of the operation of the equipment and opening of the identified valves giving rise to the correlation.  In the alternative, Ps can fine-tune Class 2 by limiting the request to specific machinery and equipment giving rise to the correlation.  Amy subsequent application for discovery may also be framed more precisely by reference to the valves identified through the Class 3 discloure.

5.21  For the above reasons, I refuse Ps’ application in relation to Class 2.

(iii)   Class 1

5.22  Class 1 seeks “The updated plans, or any plan, drawing or document, showing the current locations of the valves of each floor of the Shopping Centre, 4/F, 5/F and 6/F”.  Unlike Class 2 and 3, Class 1 represents a fundamental departure from Item 1 of Schedule I.  In its original formulation, Item 1 of Schedule I seeks 4 sub-categories, namely:

(1)  The updated Plant Room Layout Plan which shows the current routing and dimension of the pipework and location of all the valves (including the zone valves and the newly installed valves) and sensors in the HVAC System of Admiralty Centre;

(2)  The updated Pipe Routing Plan which shows the pipe dimensions and all valve locations (including the zone valves and the newly installed valves and associated sensors) in the HVAC System;

(3)  The as-fitted drawings of all the Modification Works (defined in item I of Schedule II) showing the actual status and condition of such works at the time of their completion;

(4)  The designs, plans, procedures, stage work drawings, layout drawings, detail of plants, schematics and diagrams submitted by the 2^nd Defendant to the 1st Defendant with regard to the Modification Works (defined in item 1 of Schedule II).

5.23  Class 1 does not relate to Items 1(3) and (4) of Schedule I.  Class 1 not only seeks to counter D1’s submission that the request for the entire Subject Building is irrelevant by limiting its scope to the Shopping Centre and 4-6/F, but as accepted at the hearing, Class 1 represents a fundamental departure from Items 1(1) and (2) of Schedule I.  The original formulation is premised on the existence of a single document showing the requested information in either subcategory, namely one Plant Room Layout Plan and one Pipe Routing Plan, and D1 has said that no such single composite plan exist.

5.24  I accept Ms Eu’s submission that such a fundamental change should not be allowed.

5.25  In any event, I am not satisfied that specific discovery is presently necessary.  Ps submit that documents showing the location of the valves are required in order to identify the relevant valves and investigate the transmission route of the Alleged Nuisance.  However, that submission presupposes that the valves requiring further investigation have already been identified.  The purpose of the Class 3 disclosure is to determine whether any correlation exists between the operation of particular Zone Valves or Subsidiary Zone Valves and the incidents complained of by Ps.  Until that exercise has been undertaken, it remains uncertain which valves warrant further investigation. 

5.26  If no correlation is identified following the disclosure of Class 3, it is unclear how Class 1 remains relevant.  Conversely, if a correlation is identified, any request for plans, drawings or documents showing valve locations may be framed with considerably greater precision by reference to the valves identified through the Class 3 disclosure.  For example, if the correlation is confined to valves serving the Shopping Centre, any further request can be correspondingly refined.

5.27  I refuse Ps’ application in relation to Class 1.

6.Conclusion

6.1  For the above reasons, I make the following orders.

6.2  In respect of the Inspection Summons, I make an order in the terms set out at §§4.14-4.16 above.

6.3  In respect of Items 1(1), 1(2), 2 and 3 of Schedule I of the Discovery Summons, I make an order in terms of Discovery Summons §1 (ie only against D1) but only in relation to Class 3 (as amended) and the remainder of those parts of the Discovery Summons are dismissed. 

6.4  At the same time of the provision of the draft order set out at §4.16 above, the parties are to also propose directions for the further conduct of the present proceedings.  By my order dated 2 March 2026 §8, I had deferred giving further directions for witness statements and expert directions to after the determination of the Inspection Application and the Discovery Application.

6.5  As alluded to above, under RHC Order 24, rule 8 where the court is satisfied discovery is not necessary at a particular stage of the cause or matter, the court has the option of either adjourning or dismissing the application.  In the circumstances of the present case, I am of the view that the rest of the Discovery Summons (ie Items 1(3), 1(4) of Schedule 1 and the entirety of Schedule II) should be adjourned sine die with liberty to restore rather than dismissed, as some of the requests may become necessary, either at a later stage of the proceedings or depending on what is revealed by the discovery of Class 3 (as amended).  For this part of the Discovery Summons, I make a costs order nisi that the costs be reserved.

6.6  As indicated at the hearing, the parties are to lodge submissions on costs in the light of the outcome.  In respect of the Inspection Application and Items 1(1), 1(2), 2 and 3 of the Discovery Summons, I direct that Ds do lodge their submissions on costs within 7 days hereof (limited to 5 pages) and Ps do lodge their submissions on costs within 7 days thereafter (limited to 5 pages).