Question 1

A twelve-story, full-service hotel with over 300 guest rooms and gross floor area of 212,000 ft², originally constructed in mid-90s, is a full-service hotel with in-house café bars and restaurant, on-site laundry, offices, fitness centre and conference/banquet rooms, making it a multi-function development.

The hotel’s ACMV system is served by two water cooled centrifugal chillers. The Building energy systems installed are somewhat outdated. The hotel has an energy management system (EMS) that is not connected to all building energy systems (e.g., the chiller, AHU, exhaust fans) and is not being used in a fully-functional way. The monthly energy billings for tenants are in agreed proportion in the tenancy agreements. From the utility / energy billing data, it appears that the hotel has peak cooling load in January, May, August and October.

The hotel has three lifts installed when the hotel was built in the 90s. There have been no lift modernization program since except for the replacement of lift hoisting ropes and hoisting motors.

In addition, the hotel uses heaters for service water heating serving the guest rooms, as well as kitchen appliances and laundry equipment.

Hotels have a wide diversity of energy uses, with spaces that may or may not be occupied on any given day, and guest rooms that are occupied by different guests with varying habits.  The historical data show the hotel serves both tourists (including weekend stays) and business guests (typically during the week).  There can be occasional to frequent occupancy rates that are higher than design ventilation rates. This results in poor dilution or removal of pollutants in the space. This is especially true for bars, conference rooms, public lobby, and hotel guest rooms.

Nearly 5 years ago, the hotel underwent a minor renovation. The renovation included installing a Direct Digital Control (DDC) energy management control system to control the variable air volume (VAV) ACMV system and lighting and a variable speed drive (VSD) for the chilled water system. The building was not commissioned as part of the renovation.

An O&M assessment was performed 3 years after the renovation because the building energy bills seemed higher than expected. As a result of the assessment, few O&M related problems including a major indoor air quality (IAQ) deficiency were identified. It was also determined that the majority of these problems had been present since the renovation.

The hotel is managed by an in-house team for daily system operation and periodic / scheduled maintenance work.  Specialised services like lift maintenance, fire alarm system and BMS are provided by vendors and service providers.   You are the Building Manager of the hotel and you have observed the existing physical system operation conditions for quite a while.

(a) Analyse the energy management system in the hotel operation and examine the challenges of effective implementation of the energy monitoring and measures to achieve the required energy savings. Your analysis should include but not limited to the following:

(i) Identify the equipment/ system for energy improvement, the potential for energy saving, reduction of energy cost, etc.

(ii) Examine and identify techniques used to monitor energy consumption and propose the approach of energy conservation techniques.

(iii) Propose approaches to monitor and measure energy usage and consumption pattern. (40 marks)

(b) Analyse what are the operation and maintenance strategies to enhance the control of IAQ. Demonstrate how M&E equipment / systems can be improved to promote better IAQ in the long term. Refer to relevant codes and regulation whenever necessary. (15 marks)

(c) Compare and examine the differences between: (i) In-house maintenance and (ii) Outsourced maintenance for the operation of the hotel. (20 marks)

Establish advantages and disadvantages of these two arrangements. Examine and recommend with THREE (3) supporting reasons the maintenance arrangement that is best for the hotel operation.   (25 marks)