Smart Building Energy Systems

INTRODUCTION

Due to the increasing use of renewable energy (RE) technologies to generate electricity, there is more need by the grid to have their customers’ loads be flexible and dynamically responsive to effectively match demand and supply while maintaining high levels of reliability and efficiency. Moreover, the use of building-integrated RE systems combined with sustainability requirements has increased the desire to electrify the building loads to eliminate any fuel-based systems for space and water heating. In addition, the recent gain of electric vehicle in the market share has started to change the profile of building electrical loads.

To enhance the flexibility of building energy demands, a wide range of smart systems have been introduced for both new constructions and retrofit applications. The smart systems that are gaining significant market share in the building industry worldwide include, but not limited to, smart thermostats, smart lighting controls, and smart security systems (Memoori, 2018). Recently, the Department of Energy (DOE) has introduced an initiative on grid-interactive efficient buildings (GEBs) to promote the development of adaptive and dynamic energy systems and strategies that increase the load flexibility of smart buildings (DOE., 2019a). Smart buildings or GEBs involve energy-efficient and integrated smart technologies as well as RE systems in order to adjust their energy demands while optimizing occupant needs, operating costs, and grid services. Specifically, GEBs are buildings that are characterized by four main features:

• • Energy-efficient through integration-proven design and operation measures to ensure reduced energy use
• • Connected with continuous communication with the grid to accommodate time-dependent signals
• • Smart with advanced controls and technologies to respond to needs of occupants, operators, and the grid
• • Flexible with the capabilities to shift and change the loads, depending on desired targets set by occupants and the grid.

The benefits of smart buildings and GEBs depend on various factors, including the needs and expectations of various stakeholders such as the grid, building owners, building occupants, and the society (Caramichael et al. 2019), as briefly outlined below. ^•

Grid. Smart buildings can be easily integrated with smart grids to provide a wide range of ancillary services to the grid to increase its reliability through DR and energy efficiency (EE) operations as well as reduce its operating costs and the need of additional power plants.

• • Building Owners. Smart buildings reduce the operating costs due to the fact that they can be flexible to adapt to any future energy rate structures.
• • Building Occupants. Smart buildings can be controlled to enhance indoor environmental quality, including thermal comfort and air quality, and thus enhance health conditions and productivity levels.
• • Society. Smart buildings can reduce the carbon emissions and increase the need for high skilled jobs to design and operate various building systems.

In this chapter, the concept of smart grids is first introduced, including some of the operation needs to balance between supplies and demands. Then, a description is given of the technologies suitable for smart buildings as well as some analysis approaches for selecting optimal measures that provide benefits for the building owners, occupants, and grid operators. Moreover, the performance of smart energy systems is discussed through case studies and calculation examples.

SMART GRID

Smart grids allow integration of sustainable technologies, including clean energy sources, reduced air pollution, and accessibility to various services (Angelakis et al„ 2017). In particular, smart grids can increase the reliability and EE of generating and distributing power to communities and cities. Moreover, smart grids allow the integration of distributed generation technologies, including RE systems discussed in Chapter 9. Smart grids go a step further by integrating communications and computer-based technologies to monitor, control, and optimize the entire power systems.

Smart grids are generally used to refer to sets of advanced control systems and technologies to operate efficiently power systems to generate, transmit, and distribute electricity to various end-users, including buildings. Typically, smart grids utilize digital data streams (DDS) combined with information technologies to enhance the integration of various components of power systems, including matching and controlling electricity demand and supply. In particular, electrical loads of buildings can be controlled and varied through communications with smart grids in order to optimize the operation of the utility generating power systems. The interactions between smart grids and buildings can occur through smart meters to transmit data about the operation settings and energy use levels of building energy systems. With these datasets of DDS, smart grids and buildings when equipped with smart controls can learn the buildings’ loads and their patterns to make better decisions in electricity demand and supply.

The following are the main components of a smart grid that allow for two-way communication interactions between the grid and the end-users, as illustrated in Figure 11.1: ^[1]

FIGURE 11.1 Basic electricity and information flows for a smart grid.

Some of the advantages of smart grids compared to the traditional grids are as follows:

• • Optimization of the power generation operation
• • Ability to defer electricity generation, transmission, and distribution capacity
• • Minimization of ancillary service costs
• • Reduction of congestion costs
• • Decrease in equipment failures and wide-scale blackouts
• • Minimization of maintenance costs
• • Reduction of meter reading costs
• • Decrease in electricity theft
• • Reduction in greenhouse gas emissions

The optimized operation of energy systems can be carried out at different scales starting from small systems to large systems. For electrical grids, the proposed scales include:

• • Individual equipment or systems in a building
• • Individual buildings
• • Nanogrids (communities and campuses) or microgrids (cities)
• • Regions and states
• • Countries (country-wide coordinated system)
• • Continents

While a traditional grid attempts only to meet specific loads from end-users using the available generating capacity, a smart grid tries also to manage electricity usage to shape the demand to match the supply. The loads can be shifted using DR controls from on-peak periods to off-peak periods where electricity is cheaper to generate.

TABLE 11.1

Comparison of Features and Characteristics of Smart Again Traditional Grids

maximize the transmission of real power. Frequency responsive reserve and inertial response enhances capabilities of the grid to quickly response (within seconds) following a contingency through generators and DR programs. The energy imbalances are generally provided supply and demand resources during periods when there are differences between scheduled and delivered electricity.

• [1] Smart meters to measure end-uses and other key drivers of electricityconsumption • Management tools to account for both demand and supply of electricity • Information technology systems • Building energy management systems • Intelligent or smart electricity consuming equipment such as appliancesand air conditioners (ACs)