October 2010


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Load Shaping for Net Zero Buildings

Load shaping prioritizes energy use by prioritizing systems, matching demand to supply within the microgrid.

Toby Considine
Toby Considine
TC9 Inc

The New Daedalus

Contributing Editor

Management of load shape will become a new source of value in Net Zero buildings. Smaller operating margins will increase the cost of overshooting energy budgets even briefly. New market models will create costs for undershooting as well as over-shooting energy use. Off-grid facilities will want to fix energy use to supply precisely. Storage management and even privacy create new incentives to precise energy use.

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Load shape is the chart over time of how much energy is used. Each system in a building has a load shape. A refrigerator has a simple recurring load shape. An air conditioning system cycle has a load shape that will vary based on outside temperature and room occupancy. The building’s load shape is the sum of all the load shapes of the systems within the building.

It is easiest to consider the value of managing load shape when considering an off-grid scenario. There is a knowable and fixed amount of electricity available. The building load is dynamic, composed of many systems each on its own cycle. The peak load used by each system is less than available power. If the peak load from two or more systems coincide, they can exceed the available power, and damage the other systems on the internal grid. Top shape load, one system can be delayed for a few minutes, or another can be accelerated, maintaining service while never exceeding supply.

The electricity source is solar PEV providing a predictable yet intermittent energy supply. It is necessary to store energy while the sun shines for times when it does not. Storage management may involve managing battery charging, or it may require pre-use. Pre-use may involve a variety of physical processes, such as pre-cooling or pre-pumping water. Each pre-use scenario has its own load profile.

[an error occurred while processing this directive] Load shaping manages the existing electrical supply for maximum utility while storing all excess supply in some form or another. It avoids peaks, and uses the troughs in energy use. Load shaping prioritizes energy use by prioritizing systems, matching demand to supply within the microgrid.

As energy markets become dynamic, the most valuable customer is one whose load is predictable. Today, load variance is statistical noise within the grids operating margins. As we reduce the operating margins of our smart grids, they will have less ability to absorb variability. Customers may have to purchase variability on energy spot markets.

Some consumers today already protect themselves from price variability by making committed purchases of energy. Customers using more than the committed load can incur substantial costs. Using any less than a committed purchase is leaving money on the table. Site-based storage as a complement to load shaping supports customers on both sides of the committed load. Customers in more dynamic markets with higher prices will benefit from load shaping just as do consumers in off-grid facilities.

The approaches and technologies that enable a facility to manage its load shape adapt naturally to shortages and outages. Facilities managers increase their demand response capabilities when they know each load, how to move it in time, and how to shape load for each level of use.

In today’s world, load shape arbitrage is a service provided by the energy supplier. Under smart grids, the cost of that arbitrage will be unbundled and it will increase. Many facilities will see opportunity in bringing that arbitrage in-house.


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