The cool factor
Temperature in and around the hotel is a very critical factor that contributes to the success of the hotel. Hotelier India explores HVAC systems and the latest innovations in this department.
As the most service driven industry, the hospitality sector has its own set of unique challenges.
A hotel stay is all about the experience, making it hard to quantify and compounding the challenge further is that it varies from guest to guest. Heating, Ventilation and Air Conditioning (HVAC) systems are critical to this experience.
Consuming almost 8-12% of revenue generation, a robust HVAC system is essential to keep operation costs in control. In addition, environmental responsibility requires hotels to reduce emission and recycle natural resources, which is also kept in mind while designing and installation an HVAC system.
Says Akshay Kulkarni, Executive Director, Hospitality Services, Cushman and Wakefield, “Temperature in and around the hotel is a very critical factor that contributes to the success of the hotel as the best of food tastes unappetising in a hot, humid, uncomfortable space; the best of beds cannot provide for restful sleep if not complimented by the right temperature and the taste of the best cocktail cannot be savoured unless it is the right temperature not only in the glass but also the ambient temperature.
The HVAC systems of a hotel not only contribute to the front of the house but also to the back of the house efficiency by providing sufficient heat for the laundry and in heating at times, and most critically by controlling utilities costs.”
Considering that the hotel space caters to a variety people with each individual having a different temperature threshold, it seems almost impossible to be able to satisfy all but the truly successful operations attempt to keep temperatures acceptable to most people.
Indoor Air Quality
Fresh air plays a crucial role in maintaining healthy indoor air quality (IAQ). The quality of indoor environment has an impact not only on guest comfort and their perception of quality but also on productivity loss.
“In our resort we use high efficiency fan coil units (FCU) filters capable of removing micro-organisms, these are cleaned/serviced on a regular basis. Our drain trays and drain pipes are installed with sufficient slopes, thus eliminating the possibility of moisture build up in rooms.
We do not have carpets in our rooms; however the finishes and wall coverings used are made of low VOC (Volatile Organic Compound) materials,” says George Joseph, chief engineer, The Zuri Kumarakom, Kerala Resort & Spa.
Adds SK Mishra, manager, engineering services from Hotel Sahara Star, “We are achieving indoor air quality through AHU pre-filter, apart from that sufficient treated fresh air is provided.
AHU/Fan filter cleaning on regular interval, advance BMS system is adopted for find out the position of filter and AHU room house keeping is done on regular intervals.”
Studies have proved that the level of contaminants in the indoor air can often be several times higher than outdoor air. The solution to the problem of pollution is dilution or increased ventilation, which runs contrary to the energy conservation guidelines followed by air-conditioning designers for hotels.
“The HVAC system is designed to filter the air, heat or cool as necessary, and control relative humidity during the cooling season.
“Today, systems need to be designed to cater to fresh air during this process to dilute building contaminants. A poorly maintained HVAC system can allow water to build up in the unit, creating conditions where the system itself can become a reservoir for biological contaminants.
Inadequate systems can also allow high moisture levels that foster the growth of mold and mildew. For these reasons, it is very important that HVAC systems be maintained very well,” says Sonali Dutta, vice president, corporate affairs, Pahwa Enterprises. Adds Rajan Kinjawadekar, chief engineer at Ibis, Pune,
“In guest rooms, FCUs are provided with auto solenoid valves on chilled water supply line. Those are electrically controlled by the thermostat unit fitted on the wall and accessible to the guest.
The required temperature is set on the thermostat. Depending upon the return air temp to the FCU, solenoid valve controls the flow of chilled water (CHW) to the FCU coil. When set temperature is attained, solenoid valve bypasses the CHW to the FCU coil thereby reducing the load on CHW circulating pumps and the chiller plant automatically.”
Sick Building syndrome
Sick building syndromes (SBS) are usually related to poor indoor air quality and can be caused by mould, smoke and chemical pollutants. SBS symptoms like headache, nausea, fever, dizziness, eye or skin irritation, dry cough or fatigue may lessen or disappear when occupants are outside the building. SBS can be controlled or eliminated by removing the source of the contamination, improving ventilation.
ASHRAE and ISHRAE have set guidelines for human comfort level, which are adhered to by most hotels. Striking a balance between fresh air intake and reducing in air-conditioning load is a catch 22 situation. As almost all hotels try to save on air conditioning tonnage by cutting back on outdoor air access, sick building syndrome is common.
The Senso-stat installed to control air conditioning senses movement in the rooms and the door open status and acts accordingly. This takes the temperature cut-off point up, while allowing fans to run at a lower speed, thereby reducing the load on the chiller while retaining air quality.
This feature will ensure that the air quality is always maintained and no sick building syndrome takes place, while also reducing energy consumption. Installing heat recovery wheels to recover chillness of exhaust air helps reverse return piping in vertical shafts of all guest rooms and public area.
Says Ujjal Majumdar, chief engineer, Jaypee Vasant Continental, “Smoke management is one factor on which we have worked on to ensure the safety of our internal as well as external guests from any fire.
All our AHUs are integrated with the hotel’s fire surveillance system which gets tripped in case of a fire. Special care has been taken to ensure compartmentalisation by the means of motorised dampers, which are integrated with fire systems, they close in fire conditions and control the spread of fire and smoke to other areas.”
Typically motors are controlled through Variable Frequency Drives (VFD) to ensure optimum usage of distribution pumps as per the set points. This ensures that only the required pumps are in operation at the required speed levels, thus ensuring optimum chilled water supply with minimum power consumption.
VFD controls the running of the secondary chilled water (CHW) pumps depending upon the CHW load. Depending upon the set SA temperature, the CHW flow to the consumer is regulated automatically with the help of motorised valve through the BMS.
Once the set temperature is reached, CHW gets cut off. Hence the load on secondary CHW pumps also reduces.
“We have divided our hotel in four zones namely the guest room, public areas, kitchens and back of area towards the optimum usage of distribution pump for distributing chilled water as per load set points and operation time.
Distribution pump have provided Variable Frequency Drive (VFD).
These VFD works as per actual load on chiller with the help of Building Management system, as all the chilled water line are equipped with Automatic Actuator valve which work on a particular set point on each unit once the set point is achieved, the Actuator valve closes and blocks the flow of chilled water through a cooling coil which ultimately reduces the load of secondary pumps and once the load on secondary pump reduced, VFD reduces the speed of pump through a sensor installed at the top most point of the chilled water line of each zone,” says Mishra.
With the advancement of the green building movement in India, hoteliers are keen on adopting a holistic green design and construction framework for their upcoming facilities.
Many properties in India are going for LEED or GRIHA ratings and HVAC controls and BMS play a crucial role in winning key points on energy efficiency.
Having an Energy Management Plan, with a list of projects and priorities is a good idea as HVAC itself accounts for 50-70% of total energy consumption, which is 10-15% of hotel revenue. Sensostats are normally used to control the Fancoil units installed in rooms.
When the set temperature is achieved, the motorised valve cuts off the chilled water supply through the coils and brings down the fan speed.
“Also when there is no movement in the room or when the doors are opened, the cut-off temperature point is automatically raised and the fan speed is brought down to a lower speed. Additionally the Sensostat is fully programmable to suit our requirements,” says Joseph.
Packaged Terminal Air Conditioners (PTAC) units are also becoming popular. This is a self-contained air conditioning unit that is installed through an outside wall rather than through a window.
One unit goes into each room and each is controlled independently. All the units can be controlled from one point i.e. from reception as well. Most of the PTAC units are made for both heating and air conditioning.
An advantage of PTAC installation over traditional central heating and air conditioning is that PTAC units, since they are installed through outside wall, do not need duct work cutting down time and space needed for installation.
“Building costs can be reduced by 10% to 12% and air-conditioning cost by 20% to 30% by incorporating Heat Wheels. Add to that the lifelong savings in energy costs. We as nation must push forward and institute these changes for ourselves and our future,” says Rahul Aeron, national manager sales, Desiccant Rotors International.
Mukesh Dharmani, director engineering, The Imperial New Delhi adds, “We have installed intelligent key card systems in the guest rooms which help us to save electricity and also the room temperature in case the room is unoccupied. For public areas Thyristor controlled dimmers installed for lighting and the AC units operated through VFDs, save energy.”
The HVAC industry is looking closely at how energy inefficiencies in equipment contribute to greenhouse gas emissions. Johnson Controls has identified several technologies that help building owners and system designers reduce CO2 emissions, which is a greenhouse-gas reduction (GGR).
“The latest technology in air conditioning systems is the inverter unit which enables uninterrupted comfort and significant energy savings. With no voltage peaks, it’s more economical, more powerful, more comfortable and quick with cooling and heating.
Another new HVAC technology is Green Refrigerants. They are primarily working fluids used for heat transfer in air conditioning system.
Refrigerant gas used in commercial refrigeration and air-conditioning (RAC) systems or HVAC systems is comprised of hydro chlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs),” says Seemant Sharma, director and general manager, ES, Building Efficiency, Johnson Controls India.
Likewise, Honeywell Environmental and Combustion Controls (ECC) provides cutting edge technology in HVAC controls and water management solutions for the hospitality sector.
“HALO, Honeywell’s digital thermostat with its large display, sleek looks, user-friendly and energy saving features are tailored for temperature setting requirements of guests in hotels.
The dual set point feature allows automatic switching to energy saving mode on no-occupancy detection using the input from key switch or an occupancy sensor,” says Ninad Pradhan, business unit head – Honeywell Environmental and Combustion Controls.
Alerton’s BACnet®-based VisualLogic® Display (VLD) is an ideal offering for the hospitality industry. VLD is a communicating, intelligent sensor-controller combination with built-in temperature and humidity sensors suitable for control applications such as fan-coil units and hotel room controls.
Honeywell has recently launched the Kombi 8 series of pressure independent integrated balancing control valves for accurate linear temperature control of air conditioning design.
“The government has taken active steps to mandate the reduction in the consumption of the currently used refrigerant by 2015 and so the HVAC industry has to react immediately and aggressively. New refrigerants are being talked about now which have a low GWP (Global Warming Potential).
We have a responsibility to offer technologies and solutions that have the least impact on the environment,” opines Arup Majumdar, global program director, Emerson Climate Technologies.