Energy Factor and water heating technologies

A different sort of green home

According to the US Dept of Energy's website, energy factor (EF) indicates a water heater's overall energy efficiency based on the amount of hot water produced per unit of fuel consumed over a typical day. This rating applies to a variety of water heater equipment: tank-style (storage), tankless/on-demand, and heat pump water heaters (HPWH).


Solar water heating has a very similar rating called the Solar Energy Factor (SEF).  Solar equipment is evaluated for thermal performance efficiency by an organization called the Solar Rating & Certification Corporation (SRCC).  The federal tax incentives for the installation of solar equipment are contingent on the solar water heating equipment having been evaluated by the SRCC.  The SRCC developed the SEF for the purpose of comparing solar water heating systems to a standard 50 gallon residential water heater in an apples-to-apples sort of way. Many natural gas utilities use the industry standard EF rating system to award rebates for high performing water heating equipment.  Since SEF is the solar equivalent of EF for a standard water heater, my view is that solar water heating systems that meet EF ratings for high performance equipment should qualify at a minimum for the existing utility rebate programs.


So how do different water heating technologies measure up with respect to energy efficiency?


Tank storage water heaters

Bradford White 40 gallon gas water heater

Typical residential storage water heaters range in size between 40 and 80 gallons.  This volume of water is heated up to the desired temperature (120 degrees F); the heating element or burner cycles on and off as a thermostat in the top portion of the tank detects adequate heat or not.  This is usually the least expensive water heating technology to install but is also normally the most expensive to operate. Recovery of the heat in the tank during and after use can be slower than with other water heaters which leads to the cold showers in high use situations.


EF rating for gas heated tank water heaters:

• Low efficiency -- < 0.62
• Medium efficiency -- 0.62 to 0.67
• High efficiency -- 0.67 to 0.82

EF rating for electric heated tank water heaters:

• Low efficiency -- <0.90
• High efficiency -- up to 0.95

Keep in mind that EF rating is only with respect to the energy efficiency of the appliance.  The electricity that heats the water in an electric tank model could be coming from sources with varying degrees of efficiency and environmental impact.

Tankless

Tankless water heater (top right) in conjunction with a solar water heater

Also called on-demand water heaters, these units heat water as it flows through the device.  They are capable of reducing water heating costs 10-20% due to the elimination of standby losses (constantly heating a tank of water even when no hot water is needed).  Tankless units come in electric, natural gas, and propane versions for different markets.  Not only are these a bit more energy efficient than tank style water heaters, they are also compact, wall mounted devices to save space in the mechanical room and they can provide almost unlimited amounts of hot water.


The EF rating for gas-fired tankless units ranges between 0.82 and 0.96. 


Heat Pump Water Heaters

From DOE

In a heat pump water heater, electricity is used to move heat from the air around the HPWH into the water tank versus directly heating the water with resistance coils.  Since the heat pump cycle can take a significant amount of time to heat or reheat a tank of water, electric resistance coils are included in HPWHs to augment the recovery of the water heating and thus minimize cold shower scenarios.  HPWHs can be very energy efficient and cost effective when the HPWH is operating in the heat pump mode; they revert to EF ratings of electric water heaters when the resistance coils kick in however.  Like with many things in the sustainable building world, efficient design is only part of the total picture.  How something is used in the real world effects its overall efficiency. 


EF ratings of HPWH in hybrid mode is 2.20 and fall off towards 0.93 in electric mode (average ~1.60).


Solar Water Heaters

In solar water heaters (SWH), the heat from the sun's radiation is transferred to drinking water during the day and stored in a tank of water for use throughout the day and night.  In homes where a 40 gallon tank water heater is appropriate, you'll find a 60 gallon solar storage tank. Because the amount of energy to move the heat from the solar collectors to the drinking water is minimal and the sun's energy is free, the operating costs of SWHs are the lowest of any water heating technology today. They are also the lowest carbon option when the system offsets fuel from gas appliances or electricity from coal-fired plants. SWHs have the highest upfront cost in the water heating space, but federal and state incentives exist to encourage their adoption since they provide a benefit to both the system owner and society as a whole.


Calculating EF from the SEF rating developed at the SRCC is done with the following equation: SEF x (1 - SF) = EF. SEF and SF (Solar Fraction) are calculations from the OG-300 report on each system found at www.solar-rating.org. EF ratings on SWHs range from 0.93 up to over 5.70 depending on the size of the system, location, and back up fuel option.


Summary
The less you pay upfront for a water heater, the more you pay over time.  As fuel prices of all sorts rise in the future, an investment in efficiency today will pay increasing dividends over time.

How to sell a solar water heater in a market with cheap natural gas

With the price of natural gas at a historically low point, selling a solar water heating system in natural gas water heater markets is a tough proposition. While we have to address return on investment as solar professionals, there are many other factors that go into a customer's decision making process about going solar. Solar water heating isn't for everyone so broad brush approaches won't work. The key is to target the right audience with the right message before you spend much time or money. The following is a guide to help you do this.

What to talk about

John Cole Cartoons

People are interested in distributed solar energy for a number of reasons.  Residential solar water heating continues to be an exceptional option in the portfolio of clean energy choices a homeowner has.  Energy cost savings is just one aspect of a clean energy purchase.  Make sure that you are talking about all the other reasons for pursuing solar.  Here are some good ones to start with and expand upon:

• Solar water heating (SWH) is a cost effective way to reduce home energy consumption by over 10%.
• Like electric vehicle purchases, SWH is a visible commitment to clean energy for a much lower sticker price than any car.
• When built into a new home, the net cost of a SWH is on par with the cost of a tankless water heater yet SWH outperforms tankless units in energy savings (EF of 0.82 for tankless vs 1.4 for SWH)
• While low now, the price of natural gas is set to rise with growing demand from electrical generation and transportation as well as with increasing scrutiny of hydraulic fracturing (fracking) practices. A SWH installed today is a hedge against rising fuel prices.
• Talk about the avoided costs & externalities of fossil fuels. Natural gas may be cleaner than coal, but it's hardly clean in comparison to solar water heating.
• Solar water heating creates local jobs--engineering, installation & service, sales & marketing, and distribution.

Tell the story to the right people

You need to maximize the impact of your messaging by positioning them in front of the right audience. The right audience is one that is both receptive and responsive to your point of view. To encourage a conversation and spur interest in SWH, the best approach is a combination of Facebook and blogging. Articles that address your messaging can't be neutral. You have to make a point either with your own blog posts or with comments on articles written by others. Your opinions may alienate some people, but those people are probably not receptive or responsive to clean energy issues in the first place--your target customer is. There are people out there who are concerned, knowledgeable, angry, and ready to act if they find a leader in their community with a solution that resonates with them. Solar is part of the solution and you are that solution provider.  Don't make any assumptions about who a receptive and responsive customer might be; stirring up a conversation about the issues that got you into the solar business in the first place will bring them to you.

Where to tell the story

Web marketing is a hot topic with lots of nuance.  It is an essential part of modern business and is redefining the fields of public relations, promotion, sales, and general marketing.  In the interests of getting you started today, I suggest working with the steps below.  Expand and modify as you get more comfortable and learn more.

1. Find an article that resonates with you and your team.  Get your friends, family or co-workers to suggest an article to post and select one.
2. Post the article to your Facebook business page (make a Facebook business page if you don't have one and encourage people to "Like" it).
3. Make comments on this post that tell your target audience why this article is important to you. 
4. Get all your friends, family, and co-workers to "Like" the article so their network sees it too.
5. Directly ask people to read and comment on your post (via email, phone, twitter, FilterTweeps,  etc).  
6. Repeat every workday.

Once you get comfortable with this daily effort, you can branch out a bit by writing your own blog articles.  Post it to your company website or some other website (Tumblr, Blogger, etc).  Use this as your Facebook link of the day and encourage the comments as suggested above.  Also while Facebook is the current dominant player in social media, explore using other sites like Twitter, LinkedIn, Google+, or any of the other growing number of websites to expand the reach of your effort.

Keep at it

Cheap natural gas makes for a difficult sales process for solar water heating. Difficult but not impossible. Continually remind yourself why you got into this business in the first place and find creative ways to connect with like-minded people. Tell people about your company and its goals.  Keep people continuously aware of your projects to build on successes. Help people connect their daily behavior to greater social trends. Be consistent, be informative, and be real. You'll begin to find that the right people will find you.