Aron Cromwell really isn’t a mad scientist.

But he does have panels full of copper pipes on his roof, gallons and gallons of antifreeze and a series of 80-gallon water tanks lined up in his basement.

“I know it kind of looks like a plumbing experiment, but it really is just how we store the heat for our home,” Cromwell told a group of city and state leaders who on Wednesday toured his East Lawrence home, which was built in 1911.

Cromwell is one of about 45 vendors who will participate in the city’s Sixth Annual Home Energy Conservation Fair on Sunday at the Douglas County 4-H Fairgrounds.

During the fair, Cromwell, an owner of Lawrence-based Cromwell Environmental, will explain how he installed a solar hot water system at his home at 1616 N.H. to provide hot water and about 50 percent of the home’s heating needs. He expects that the new system, which his company designed, will save his family $1,500 to $2,000 per year on heating costs.

The downside is that the system costs about $25,000 to install.

But it isn’t necessary to spend that much money to cut energy use and save money on utility bills.

“We’re going to show people a lot of different ways to improve the energy efficiency of their homes,” said Michelle Crank, a specialists with the city’s Waste Reduction and Recycling Division, which is an organizer of the fair. “A lot of people will be able to walk out of there with just a little bit of weatherstripping and some duct tape and be better off than they are today.”

Organizers are expecting about 500 people to attend the fair, which runs from 10 a.m. to 5 p.m. at Building 21 at the fairgrounds, 2120 Harper St.

“The energy price spike we’ve seen has been a big wake-up call for a lot of people,” said City Commissioner Boog Highberger, who attended the tour of Cromwell’s home. “Even though gas prices have dropped a little bit recently, I think the long-term trend is nothing but up.”

Leaders with Aquila, the city’s provider of natural gas, said conservation should be a major issue for all homeowners.

“That is really the one thing that they can control,” said Larissa Long, the company’s manager of external affairs.

Homeowners certainly can’t control gas prices. Last year at this time, gas experts were predicting price increases of 20 percent or more. The cold winter, though, never materialized as predicted, which helped control energy use.

This year, Long said natural gas prices are expected to be lower than last year. For example – based on current prices – an average homeowner would be expected to have an October bill of about $32 this year compared with a bill of about $53 last October.

Long, though, cautions that trend could change if the weather gets nasty.

“One forecast will tell you that we will have an extremely harsh winter, but another will tell you that it will be relatively mild,” Long said. “Just look at how the weather has been changing recently. It is hard to forecast right now.”

The fair will include information for both do-it-yourselfers and people interested in hiring professionals to make their home more energy-efficient.

The fair also will include a tour of six area homes that have been built or remodeled in a way to promote energy efficiency. Cromwell’s home will be on the tour.

In addition to the solar heating system, Cromwell’s home will produce solar-generated electricity that will provide about 75 percent of power needs for his home. That system cost about $30,000 to install.

Cromwell said – unlike the hot water system – he installed the solar electric system primarily for environmental reasons rather than a cost savings. He estimates that his retrofitted home will reduce carbon monoxide emissions by about 9 tons per year.

Other stops on the tour will include a partially underground home and homes constructed of straw bales or concrete.

Bus tours of the homes begin at 10 a.m. and 2 p.m. Sunday at the fairgrounds. There is a $6 charge to attend the home tour, but the energy fair is free.