The environmental mistake at Folsom Ranch

CaliforniaGeo 8-1-19

 Recent developments in California municipalities (Folsom & Berkeley) have been both good and not so good for the environment and the overall thrust of this state’s emissions and related policy.  Some years ago, the City of Folsom annexed an adjacent southern parcel and masterplanned it for some 10,000 residential dwellings, built out over 25 years.  A light rail line extends to the present edge of this city, but the main artery of transportation is U.S. 50, an increasingly busy connector between the state capitol and Lake Tahoe.  But transportation is not the only thing that Folsom Ranch will find challenging.

At cross purposes with regulations and policy—

Existing state regulations attempt to lower airborne emissions to improve health and to slow global warming.  In addition, the eastern foothills of Sacramento County have a summertime  afternoon ozone problem.  Bolstering AB 32 from 2006, the bill SB 1477 (signed in 2018) seeks to de-carbonize the state and recognized the preferred trend to electrify both old and new building stock.  Berkeley recognized this in mid-July with their ban on gas.


But Folsom Ranch was developed on a conventional model, so its infrastructure had natural gas woven into the project and most homes will be built with combustion furnaces, boilers, gas kitchen appliances, and gas water heaters.  It could have been different.

This project’s choice means that there will be gas leaks (of pure methane; a product over 80 times as powerful as carbon dioxide as a greenhouse gas) that will continue in this expanded distribution system for at least 100 years.  Also, in our construction era of tighter and tighter air sealing of homes, residents who use ovens and cooktops powered by gas will inhale greater concentrations of combustion waste than with older building stock.  This is a negative effect on respiratory health, particularly in children.  That costs time and money.

An alternate path—

The Folsom Ranch development could have been different.  It might have stayed closer to state regulatory policy by eliminating gas distribution lines, altogether.  The emission-free path of electrification could have been taken, and these homes and mixed use commercial buildings could have remained gas-free.  

Although it is essentially built out at this point, Berkeley took the step to eliminate any additional gas distribution or hook-ups within their city limits.  And they are also pushing for heat pump retrofits to replace existing residential gas utilization.  Other locations such as the province of Ontario Canada and Westchester County in New York state have halted the extension of gas lines in favor of geothermal heat exchange loops to serve heat pumps.   

Electrification is the name encompassing this goal, and California is not the only state supporting its expansion.  Forty years ago, electrification would not have been a sensible choice because it would have required more (likely fossil-fired) generation that fouled the air.  But today, wind and solar are expanding the renewable fraction of electricity on our grid.  California is already ahead of its goal of 33% renewable power by 2020 (and this doesn’t count  its established, long-term hydropower).

Geo heat pump option?—

As more vehicles and new housing become electrified, the fraction of greenhouse emissions still tied to buildings will increase, including the long, fossil-based life of these new buildings at Folsom Ranch.  This large project could have been provisioned with geothermal heat pumps for heating, cooling, and hot water pre-heating.  

There could have been a large district loop serving everyone for a monthly utility fee far less than the cost of piped-in natural gas.  This is the method that serves a growing set of large scale developments such as Whisper Valley, Texas northeast of Austin, and Serenbe in Georgia.  That lower cost comes from tapping a free thermal resource on-site and not having to pay for importing it from far away.  Electricity goes to all new buildings within any development anyway, so the resource for electrification will already be present.  And with that, individual solar PV can intertie to the grid to export electricity, banking it for later use at night or in peak heating or cooling seasons.

Quality of life—

If this project would have been provided with geothermal heat pumps, the air in eastern Sacramento County could have been cleaner, residents healthier, summer grid peaks lower, neighborhoods quieter and cooler in summer, and HVAC equipment would have lasted longer.  Geo heat pumps have an inherent advantage when it comes to heating and cooling of occupied space.

First, consider the function of insulation in adequately weatherized buildings.  Insulation buys you a thermal time delay.  What, you say?  In winter, good insulation can keep the cold away from your interior space longer, getting you closer to the outdoor warming period of the morning, and saving your HVAC system from having to respond to the cold outside.  The same is true for summer cooling.  Insulation (and proper attic ventilation) can delay your need for cooling longer than a building without such protection.  And, you may not need to task the HVAC system for cooling during the afternoon grid electrical peak of summer.


Now, consider the geo heat pump compared to conventional air conditioning or an air-source heat pump.  Insulation can only take you so far.  When you need summer cooling, the conventional system has to push unwanted interior heat into outside air that might be 95°, and the ability to transfer that heat (by convected air) is a challenge.  The geo heat pump transfers unwanted heat into liquid water (by direct conduction) and water is 3,000 times as dense as air for an effective heat transfer pathway.  In addition, the geo loop travels through an underground medium that stays almost constant in temperature.  In summer, that formation might be as low as 70°.  It takes far less time to eject the heat you don’t want, and that means your equipment consumes less power.  [Today, at my house on August 1st, the daytime high was 90° and when cooling kicked in at 5:45pm, the dirt at 7-feet was 61.6° and the incoming water to the heat pump was 69.3°.]

Next winter, in the wee hours when an air-source heat pump would work to capture and transfer heat from the outside air, the geo heat pump would be transferring heat from an underground formation that might be 30° warmer.  Again, this means less run-time, while heating water simultaneously.

The future—

Folsom Ranch wasn’t what the policy makers or efficiency experts hoped for, but there will be other developments.  As the trend toward electrification continues, more people who cook with gas will follow restaurant chefs into induction cooking, and the successes of growing geo heat pump utilization will wake the public to this superior way to obtain comfort at less cost while being very green and benign to the environment.