The four pillars of Building to Grid (B2G)
By EnPowered - July 13, 2021
Automating building systems and connecting properties to the grid as responsive assets is a key way to improve grid stability and efficiency. EnPowered simplifies energy management.
Buildings are responsible for 80% of US Peak demand and 12% of emissions, so reducing energy use and emissions in buildings can have a substantial impact
Automatically tailoring loads based on weather, season, time of day, occupancy, and operational intensity boosts energy efficiency, while on-site energy storage increases facility resilience
Incorporating renewable energy - including behind-the-meter generation sources - ensures energy diversity and reduces risks from outages: all these elements ensure greater grid flexibility
You’ve heard of B2B and B2C, but do you know what B2G stands for? B2G means ‘building-to-grid’, and it involves integrating buildings into the grid not merely as energy consumers, but as responsive assets that can engage in two-way communication with the electrical system. Building-to-grid is part of the wider movement to create smart spaces and equipment by incorporating sensors and communication abilities in previously inert or ‘dumb’ materials. Specifically, B2G draws on the Internet of Things (IoT), to allow entire buildings to measure energy use and respond accordingly, based on signals from the grid.
What this means is that grid-integrated buildings can increase, shift, or decrease their energy use patterns based on wider grid conditions. This helps flatten Peaks and increase grid resiliency and stability. The Office of Energy Efficiency & Renewable Energy describes the B2G paradigm as enabling “[...] buildings to act as shock absorbers for the grid.”
Buildings are responsible for 80% of Peak demand and are the source of 12% of US emissions, so there is substantial potential to both reduce energy use and emissions by ensuring buildings meet B2G standards. The Department of Energy explains that “[...] transforming demand response devices to be fully dispatchable could save billions each year in reduced energy costs.”
One way to use B2G is to convert government building portfolios as a way to demonstrate feasibility to the private sector. The US General Service Administration (GSA) manages over 8,700 buildings and according to the Rocky Mountain Institute (RMI) if B2G was adopted, it could deliver $208 million in savings over eight years portfolio-wide. Specifically, $50 million in annual cost savings (or 20% of the GSA’s energy budget), and $70 million in potential annual benefits from energy saving and grid flexibility.
What does a B2G property look like?
There are four key facets of a grid interactive building: energy efficiency, energy storage, renewable energy, and load flexibility. We are all familiar with the hardware and behavioural modifications we can employ to increase energy efficiency. Improved lighting and HVAC technologies have been discussed at length, as have building management tools that allow building users to automatically tailor energy use based on occupancy loads, time of day, or weather. Fridges, freezers, and even whole buildings can be pre-cooled to ride out the hottest part of the day in order to reduce Peak energy use. Water heaters can also be turned on at optimal times and store electricity in the form of heat which can be used at a later time.
The Pacific Northwest National Laboratory explains the idea of 'transactive energy'
We already have all the technology needed to implement B2G; the problem right now is that all these different systems cannot talk to each other. Smart building control systems that manage lighting or heating are already on the market, but interoperability issues prevent them reaching their full potential. There is a pressing need for a common, open protocol for building controls that is hardware and manufacturer agnostic. Ideally, buildings should have a unified and intelligent system that controls everything from HVAC and lighting, to plug loads, thermal or electric storage and more.
Energy storage and renewables
The second pillar of B2G - energy storage - has several connotations, whether pre-emptive energy storage through the use of water heaters and refrigeration systems, or more familiar examples, like electric vehicles (EV) and in-building battery arrays. Speaking of batteries, despite high initial costs, according to the RMI the losses from just one hour without electricity can be $2,368 for a primary school, $5,317 for a large hotel and $14,365 for a large office. We have already looked into the potential for EVs to act as energy storage for the grid, and these vehicles can also be plugged into a bi-directional charging station to power buildings during Peak hours or during an interruption in power. The RMI has also shown that in-building battery systems can also be economically viable if a building is subject to utility rate structures with demand charges as low as $9/kWh.
Thirdly, incorporating renewable energy is another important element of B2G, as this reduces emissions and renewables like solar are often cheaper than fossil fuels in many regions. Accessing renewable energy can also help combat intermittency, as buildings (using EVs or battery storage) can act as storage capacity during times of excess renewable generation. Behind-the-meter green energy generation is also important to consider.
On-site renewables generation (such as solar or geothermal) can be used to both power local operations and/or be provided to the grid on a dynamic basis based on load profiles. One example is Alabama Power’s Smart Neighborhood initiative which currently encompasses 192 lots over seven locations. Not only do these properties boast on-site renewable generation, they are also B2G ready, with bidirectional EV charging stations and automated HVAC and lighting systems.
The fourth and final pillar of B2G is grid flexibility, something that the previous three pillars all contribute towards. B2G aims to create lower and flatter Peaks and a more flexible load profile for buildings. Matt Jungclaus, writing for RMI explains that
“there is much more value to building operators in consistent demand management to reduce peaks and maximize load flexibility. Lower utility peaks and more flexibility can reduce costs in today’s grids with today’s pricing structures, while also being relevant in a future with more developed rate structures.”
Ideally, B2G structures should have the ability to track building demand and predict patterns to limit Peak demand by rapidly shifting or shedding load. This goes beyond current efforts as “even buildings engaged in curtailment or demand response programs do not often have an automated process and virtually no buildings automatically shift loads based on real-time changes in utility price signals,” says a RMI report.
The current grid system does not exchange necessary information between assets or between assets and the grid. In B2G, grid interactive buildings should receive utility price signals from the grid and share data on the availability of flexible loads within buildings. Buildings are rarely designed or retrofitted to reduce Peak demand, instead any efficiency modifications focus on reducing energy use and cost. Being able to reduce energy demand and increase flexibility behind-the-meter will be a vital step in combating growing Peaks and reducing emissions.