Towering high rise structures are beginning to dominate Colombo’s skyline. In the context of creating sustainable buildings, the efficient delivery of basic utilities; electricity, air-conditioning and water, become an integral component of their design.
The delivery of water in high rise buildings is especially challenging, as it requires transporting a significant weight, vertically! It is traditionally tackled by installing large water tanks at the top of the building. And using Booster systems to increase the pressure for the top floors, while sufficient water pressure is provided to the rest of the floors through the force of gravity. This method however incurs significant costs both at installation, due to the added concrete reinforcement work needed to support the weight of the tank on the top floor, and during operation, as a lot of energy is wasted pumping all the water to the topmost floor from the ground before letting it flow back down to each of the floors.
The efficiency of this process can be significantly improved using new technological and design innovations, which will help reduce maintenance costs for future tenants. In this article we look at how the above water distribution system for high rise buildings can be improved using such innovations.
Intelligent electronic control systems help reduce energy wastage (P2)
Intelligent Pumps and Variable Speed Drives
Water pump systems in high-rise buildings consist of multiple pumps connected to a pressurized water buffer and an intelligent electronics unit which regulates the water pressure of the entire system. This allows water to be distributed efficiently throughout the building with minimal energy wastage. The two types of pumps commonly used are; horizontal and vertical multi-stage pumps. Of these 2 types, vertical multi-stage pumps are prefered by developers as they offer the highest efficiency and reliability, as well as require significantly less space to be installed.
Both horizontal and vertical multistage pumps can be equipped with Variable Frequency Drives (VFDs). This allows the pumps to operate at lower speeds, determined by the requirement of the building. By connecting these VFD equipped pumps to a control unit, the system intelligently plans the turning on and off of these pumps based on the consumption patterns of the building, resulting in maximum energy savings. VFD pumps can also be combined with non-VFD pumps, to enjoy similar energy saving benefits to a system using only VFD pumps while reducing on the total installation cost. VFDs are used in many different types of motorized systems including air conditioning systems. You can find out more information about how VFD pumps improve Central Air Conditioning Systems in our article here.
An appropriately sized water buffer helps improve the systems overall efficiency (P3)
A Pressurized Water Buffer
Having a pressurized water buffer helps save energy by preventing the pumps from turning on every time water is used; in a tap, commode, or shower. A pressurized water buffer, also known in the industry as an expansion vessel or an accumulator tank, can be installed anywhere in the system between the pump and the outlets.
Installing a buffer with a capacity that is a multiple of the volume of water consumed by an outlet such as a shower or commode ensures that the pump system does not need to turn on everytime someone takes a bath or flushes a commode. It also prevents damages caused to the pumps due to water falling down the pipes during a sudden loss of pressure, in an event known as a water hammer. However there is a trend to undersize this pressurized water buffer and therefore it is important that more buyers are aware of the benefits of installing an appropriately sized one.
Multiple pump systems like the one shown on the right can be up to 25% more energy efficient than a single pump system shown on the left (P4)
A Zonal System Design
Traditionally a single pump system, consisting of multiple pumps connected in series, is used to supply water to the entire building. This method requires a single pump system to manage the pressure across all the floors, each of which require a different amount of energy to pump up to. To maintain a similar water pressure across all the floors, the pump system is usually sized based on the requirement of the top floor and a pressure reducing valve (PRV) is installed for the floors below to reduce the pressure of the water they receive. This system is therefore energy inefficient, and an alternative zonal approach can be utilized to save this wasted energy and improve the systems overall efficiency.
Dual or multiple pump systems connected in parallel can be used to provide water to blocks of floors. By equipping lower floors with lower rated pumps and higher floors with higher rated pumps, a consistent water pressure can be maintained throughout the building at a lower energy cost. Many hotels have reaped the benefits of this system, especially during times of low occupancy, thanks to an intelligent zonal system, which regulates water pressure to the different sections of the hotel according to their need.
Zonal system installed in a hotel (P5)
The above considerations should be taken seriously by developers looking to construct sustainable, high-rise mixed development projects. These technologies not only provide long term energy savings for the occupants of the building, but also allow the developer to receive higher energy saving certifications. It is important that buyers inquire with their developers into the water pump system planned for the apartments when purchasing them on pre-sale. For more tips on selecting the right apartment please click here.