2021 Webinar Series - 6 Electrifying Existing Buildings Part 1

Converting to Low Temperature Distribution – Many existing buildings have HVAC equipment and distribution systems that were designed for higher temperature air or water from furnaces and boilers for space heating. Panelists will provide perspectives on converting these buildings to various types of lower temperature distribution for heating, ranging from minor modifications to extensive changes. This is Part I since we will be focusing on the impact of building envelope upgrades on building converting to heat pumps in a future session. Register here:


• Jay Egg / Egg Geothermal

• Cary Smith / The GreyEdge Group

• Jeff Urlaub / MEP Geothermal







  1. Jay - the low temp water heaters appear to be larger (wider) than the steam radiators in my house that are about 20" high and 30" wide .  Do they need to cover a larger area to deliver the same amount of heat?  Who is the lead supplier of low temperature radiators?
    1. One Manufacturer is Yates: http://nhyates.com/lunch_and_learn/low-temperature-high-efficiency-radiators/
  2. How do you cool if you only have radiators?
    1. You can't really cool without adding a fan coil, or a modular heat pump. You can use chilled beams, which are like radiators in certain ways, but normally are installed overhead, because "cold falls".
  3. For Jay:  can you share any information about the cost of the Bronx project relative to a "traditional" approach, in terms of upfront and operating costs?
    1. Because the cooling tower is at the end of it's useful life, the upgrade to geothermal has a premium of about 20% for the loopfield.  The operating costs are about 22% less (than the natural gas currently used at the central boiler) when you compare savings of natural gas to added electrical load for the heat pumps.
  4. To clarify the difference between VRF and DGX... There are many DGX systems also that are hydronic, so DGX to water units and water distributed around the building (same as the water based geothermal units) with smaller outdoor loop footprint.
    1. Well said, Craig. DGX can be hydronic, so DGX to water units and water distributed around the building (same as the water based geothermal units) with smaller outdoor loop footprint. Perfect
  5. What is the EUI for Ball State? EUI it's not the total, it's the density of energy use per sf per year (what it takes to heat & cool a building)
    1. Answered Live
  6. Is there evidence of long term heat retention (soils that don’t return to normal far field temperature) with multiple  vertical bore hole fields?
    1. I'd love to talk about that one live, John.  Thanks for your heat emitter fundamentals slide! 
      1. Summary of live comment: long term heat retention is engineered out of being a problem with sound engineering practice such as proper loop field size, hybrids, and surface/groundwater exchange
  7. Is the Empire Building Challenge part of the Community Heat Pump Systems (PON 4614)?
    1. No.  Separate program from NYSERDA PON 4498
  8. It seems that the trend towards converting downtown office buildings towards mixed-use that includes apartments provides a great opportunity for heat pumps by providing a balanced load with different operating cycles and greater need for domestic hot water!  So it's not only good for smart growth and less driving but also for building energy use!
    1. Thank you, Well said!
  9. Which refrigerants that are energy efficient are also toxic/flammable?  How to think about that?
    1. The new refrigerants are called A2Ls. It's just important that these are kept outside of occupied, and codes are more stringent.
  10. It seems that reducing load through envelope measures would pair well with low temp conversions. Have there been examples of these two approaches working well together?
    1. In a few weeks we are going to focus on the interaction between building envelope upgrades and heat pump conversions.  So if we don't get to it here tune in June 1st Electrifying Existing Buildings - Part II: Role of Envelope Improvements
  11. Jeff - Can you discuss the effect / benefit of load diversity on the design for the ice rink?
    1. Answered Live
  12. How do you see the combination of factory-sealed refrigerant “boxes” combined with low temperature hydronic distribution competing against the current strong market for VRF systems?
    1. Piping refrigerants around a building is not necessary, and can be unsafe.  The hydronic solution provides the same end result of cooling and heating in each area, and is safe for occupants.