MB Civic

Alt-E Saturday: The Load Inventory
by Richard Cranium
Sat Jul 15, 2006 at 07:35:46 AM PDT

Each Saturday, I’m bringing the Daily Kos community a politics-free article on alternative and renewable energy sources, energy efficiency, and technology. There’s a lot that each of us can do (besides bitching) to make the ongoing energy crunch just a bit more bearable and less costly. The extreme upside, and goal for a lot of people, is total energy self-sufficiency. For most of us, particularly those of us in urban areas, such a goal isn’t completely practical but is still worthy in terms of lowering our own energy costs and conserving resources that are rapidly dwindling.

This series isn’t really intended for alternative energy wonks, or those already off the grid. It’s more of a conversation starter for those who’ve never given the topic a lot of thought until recently. I’d really appreciate it, though, if the wonks in the crowd would chime with their own stories and recommendations and links.

Below the fold, you’ll find this week’s article: Understanding how you use energy in your house by conducting a load inventory.

The Load Inventory

In my introduction to this series last week, I said that jumping into the world of alternative energy can be daunting for a beginner. The starting point in any discussion of moving in the direction of a sustainable energy strategy for the home is understanding how and where energy is used. It’s important to know this for several reasons, but at the highest level, as I said last week, every dollar saved in gaining efficiency is going to have a tremendous payback in the overall cost of any alternative energy system for anyone deciding to move in that direction. As Homepower Magazine writes:

A 20 watt compact fluorescent will put out as much light as a 75 watt incandescent bulb, and last a lot longer. Outfitting an entire home with energy-efficient lighting will save you hundreds or even thousands of dollars worth of extra photovoltaic modules. The same is true for efficient refrigerators and freezers–efficient units use less than 1/4 the energy of inefficient units. Every watt-hour of energy you don’t consume is a watt-hour you don’t have to produce, convert, and store.

We are not talking about sitting and freezing in the dark, but doing whatever we choose to do in the most efficient manner possible. Energy efficiency pays big dividends in renewable energy systems…

The first place to start gaining efficiency is taking a look at thermal and non-thermal energy uses. Examples of thermal energy use (basically, anything that needs heat) could include a water heater, furnace, clothes dryer, or stove. An electrical appliance in any of these roles can consume as much as twice or three times the energy dollar. The investment in a natural gas or propane equivalent can have an almost immediate payback. I can’t stress enough that moving thermal loads off of an electricity source is probably the most critical energy efficiency move that can be made.

Now let’s take a step down. The middle of summer is a great time to do an electrical load inventory. What’s a “load inventory”? Essentially, a list of where electricity is being used in the home, broken down into a couple of macro categories: heating, cooling, lighting and appliances / electronics. Conducting an inventory accomplishes a couple of things. It’s a personal education in how energy is used (which you’re going to need to spec and size an alternative energy system), and when complete, allows some prioritization in gaining efficiencies.

I’m not going to reinvent the wheel on how to conduct the inventory. Homepower Magazine has combined two great articles into a single PDF file – Starting Smart – Calculating Your Energy Appetite, and Doing a Load Analysis: The First Step in System Design. The home load profile charts in the first article are worth the download even if you toss out the rest of the information. It’s absolutely amazing how much the electical load in a home can be lowered with relatively inexpensive steps to reduce wattage consumption.

The inventory has another hidden benefit that lies in my use of the word “prioritization”. After all of the research, if you decide to cover at least some of your loads with a home power / renewable energy source, you’re going to need to know what you want to power with your own home brew system, and what you’re going to want to leave to the whims and expense of the external power grid. This also helps for splitting loads into critical and non-critical categories, and will define the approach that you’re going to take in doing some basic rewiring to physically split these loads as you spec your system.

So, sharpen your pencils, grab a clipboard, and get started on the load inventory. It’s the basis for everything else I’m going to be writing about in this series going forward.