Reducing energy use through smart technology
By Philippa Martin-King
Even based on the most conservative of figures, in OECD (Organization for Economic Cooperation and Development) countries, buildings account for at least one-quarter of all energy use. Often, that figure rises to 40 % of total energy consumption, and in industry up to a half. Buildings therefore, whether residential or tertiary, can contribute meaningfully to electricity savings.
Buildings are high electricity consumers
Statistics show that in developed countries, buildings can account for up to 40 %, sometimes even 50 % of total electricity consumption. Buildings are filled with power-hungry equipment such as data centres and air-conditioning units and heating systems that switch on and off with unfailing regularity. When there is a sudden rise or drop in temperature and all the devices switch on at the same time, the power consumption surges. Building owners find themselves with high electricity bills, and utilities are left with the sensitive task of managing supply and demand in order to avoid brownouts or, in the worst case scenario, blackouts.
The California blackouts at the beginning of the 21st century drove the high-tech American state to declare a situation of emergency. Inability to manage supply and demand in real time created a shortage of electricity that left thousands of buildings, both businesses and homes, stranded for long periods without any electricity. Today, despite the ever increasing demand for more energy in developed countries, that extreme situation can be avoided thanks to the innovation of the Smart Grid and networked technology that provides for intelligent management of power use and supply.
Efficiency through automation and control
Energy savings can be made by upgrading and renovating a building's electrification and by taking energy-efficiency measures such as installing low-consumption, high-efficiency lighting systems, motors and transformers. Then, installing intelligent automation and control systems to manage and maintain them provides the means to optimize the devices further, either by switching them off entirely, by reducing use to a minimum when not needed or simply by highlighting "bad habits" that can then be corrected. For instance a 2-degree variation in temperature settings on heating or cooling systems can consume up to 10 % additional energy, which can have significant overall consequences in the long run. Solutions include presence and light detectors, timers, variable-speed drives, automated and control systems for electric motors, and PLCs (programmable logic controllers).
A long life
It's important too to consider the entire life-cycle of a building, taking into account its use of energy at all times and not just for one particular phase in its life. This is particularly relevant when one considers that the life span of a building is long in comparison with other energy consuming devices or systems. And where new constructions often have state-of-the-art energy efficiency solutions integrated in them, in existing or renovated buildings these solutions are poorly implemented. Statistics show that each year only some 2 % of existing buildings get replaced. On the other hand, 80 % of the buildings that will still exist in 2020 have already been built. So it is vital to look at how smart energy-efficiency measures can be included in renovation efforts.
In 2008, the US (United States) Department of Energy launched a zero-energy housing programme whereby participating builders commit to constructing new housing with 30 % savings on a home energy rating scale.
In Europe, countries such as Ireland, Germany and Switzerland have programmes for passive and minergie buildings. In Australia, there is a NatHERS (nationwide house energy rating system) that uses computer simulations to assess the potential thermal comfort on a scale of zero to 10 stars. The more stars, the less likely the occupants are going to need cooling or heating to stay comfortable. Typically, houses built in 1990 averaged about one star on the NatHERS scale. Nowadays, many well-designed houses have six or more. The Green Building Council of South Africa has based its own Green Star SA rating tools on the Australian Green Building Council tools and has different rating systems for different types of buildings.
Korea's real estate market is booming and is anticipated to grow by 9 % over the next few years
In Asia, the Korean government has introduced new global climate protection guidelines to reduce energy consumption in buildings and its associated CO2 (carbon dioxide) emissions. Indeed, in Korea, according to the Korean company LS Industrial Systems [see the December 2008 e-tech], the amount of energy consumed by buildings is, on average, twice as high as in Western Europe. Korea's real estate market is booming and is anticipated to grow by 9 % over the next few years. The situation offers much scope for energy-efficient solutions and constructing sustainable green- and low-energy buildings using alternative energy sources such as photovoltaic systems, hydro-electric power and geothermal power.
ICT use increasing
A major consumer of energy in buildings, not only in offices, manufacturing sites, hospitals and so on, but increasingly in private homes too, is ICT (Information and Communication Technology). It's hard to image that in some of the developed countries that are looking to reduce their energy consumption with an aim to becoming a 2 000 watt society, i.e. with an annual consumption of 2 000W per person, that up to half of that energy can, at present, be taken up by ICT equipment, of which up to 30 % is consumed in standby mode.
Need to diagnose and monitor to install correct solutions
In order be able to carry out correct diagnosis and manage energy well, it's first necessary to be able to measure and monitor use. Solutions include smart metering systems, monitoring systems and services, energy management systems and services.
From zero to negative – managing power and generating energy
There are buildings that have extended beyond zero energy consumption and that are already capable of generating power. One of these, the revolutionary Bahrain world trade skyscraper, has three 225KW wind turbines integrated in its twin towers, the sail-shaped buildings on either side are designed to channel wind coming from within a 45-degree angle between them and direct it perpendicularly through the wind turbines, thus generating from 1,1 to 1,3 GWh a year. The energy generated from harnessing the power of the strong sea winds is the equivalent of 11 % to 15 % of the total power consumption of the towers, or the lighting for roughly 300 homes.
During the Summer months in Bahrain temperatures can reach 50 degrees Celsius. Demand for air-conditioning is estimated to use up as much as 65 % of present energy demands. In coming years this is expected to increase up to 70 %
The buildings have been designed so as to minimize the effect of the strong sun, which, in the Kingdom's hot seasons can bring temperatures up to 50 degrees Celsius. During those peak summer periods the demand for air-conditioning is estimated to use up as much as 65 % of present energy demands and in coming years is expected to increase up to 70 %. Bahrain has built a large-scale district cooling system that is designed to act as a thermal energy store in provision for rising temperatures and the ensuing peak power demands. The system uses the sea to generate a centralized storing system of ice or chilled water, which is then pumped out underground to local buildings for their own air-conditioning needs. The trade centre twin towers are connected to this system by way of low-energy pumps controlled by sensor systems that metre demand and supply.
Zero energy downtown project
Another venture, the XERO Project earned one of three first-place prizes in the Re: Vision Dallas design competition. It asked the question, "What if one block in Texas became the sustainable model for the world?" The proposal is for a new zero-energy, mixed-use development in downtown Dallas. At the heart of two intersecting greenways a residential tower incorporates passive and active systems to achieve a high level of resource efficiency. The south-facing façade has photovoltaic panels that both shield it from direct sun and provide a sustainable energy source. Inside the building skip-stop elevators only stop on certain floors, which not only economises energy but forces people to take the stairs and engage in a bit of physical activity. Then, there is a ground-source heat pump and a through-ventilation system that further reduce energy use.
Dealing with the measurements
New technologies are constantly being developed to deal with the metering requirements in buildings. Rather than simply measuring and transmitting information, they use smart systems to analyse data and determine the most efficient approach. An award-winning clean-tech company based in Toronto, Canada, has developed one such system. Regen Energy uses swarm [see below] technology, controllers that act a bit like smart power switches and that determine the best times to turn equipment on and off. When several controllers are networked together they are able to learn the power cycles of each appliance and so reconfigure them to maximize collective efficiency.
There might be 10 to 40 controllers linked together wirelessly in a building, so that whenever a utility needs to generate reserve power or, for instance, there's a refrigerator that needs an extra cycle to maintain a particular temperature, using a "demand response" approach, the system is able to dim the lights and turn down the air conditioning in order to curb the power use and transfer the energy to where it is needed most.
Swarm intelligence creates energy savings
"Swarm logic" is the ability of many small devices to link together so that collectively the structure takes on a smart behaviour. In the case of smart buildings, wireless technology is used to link together a number of sensors or transducers, switches and controllers via a network to create small energy savings. When a number of low power consuming devices are linked together, a bit like the self-organizing behaviour of bees or ants, their resulting collective power saving can generate an appreciable amount of energy and avoid a brownout or even blackout.
The concept of swarm intelligence was first used in 1989 by Gerardo Beni and Jing Wang in the context of their artificial intelligence work on cellular robotic systems. They define it as the collective behaviour of decentralized, natural or artificial, self-organized systems.
Applying social media technology to the power grid to smooth out the spikes
A recent televised interview on PBS (Public Broadcasting Services) with the Canadian eco company Planet Forward talked of a mini-energy network that can help companies cut their building costs.
The project is based on both a high-tech and a low-tech approach. Low-tech simply involves working democratically directly with building managers to identify what energy they feel they can live without when the grid is stressed, for example, by raising the air conditioning thermostat a few degrees or by dimming a few lights.
The high-tech approach involves signing up for a contract with a virtual power plant and installing a monitoring system that tracks electricity usage in real time over the network. The agreement is that, whenever it's necessary, the system can hit a switch to lower the building`s energy consumption remotely. A chain of 150 supermarkets in Southern California is already using the networking system to compensate for increased energy demands on the grid when the temperature rises, thereby generating reserve power for the rest of the community. In return, it receives financial compensation for a part of any energy savings that are made. A hotel with a mission to be environmentally friendly has reduced its power demands in ways that remain invisible to the guests. Having installed measuring devices throughout the building, it has been able to adjust HVAC (high voltage alternating current) systems and shut down some of its laundry machines. Making these minor adjustments has provided it with estimated annual cost savings of USD 7 500.
Without needing to find further technologies and solutions, much can be done simply by activating all existing levers and implementing proven technologies. All the components of a smart building exist in the standardization work of many IEC TCs (Technical Committees) that deal with wind turbines, sensors, low-energy lighting systems, photovoltaics and so on. Many of these are listed in the publications contained in the Smart Grid technology sector of the IEC website.