Carbon Reduction through DHW heat pumps

A brief explanation of the technology, benefits and key considerations when integrating into building retrofits.

Building retrofits provide an effective strategy to reduce carbon and greenhouse gas (GHG) emissions from the existing commercial and residential building sectors.  Domestic hot water (DHW) systems offer an opportunity to reduce or eliminate carbon in most buildings since these heaters are often natural gas fired. 

What is this technology?

Replacing a natural gas or propane fired domestic hot water heating system with a heat pump can have a positive impact on reducing a building’s carbon footprint. 

Using electricity to drive a compressor, a DHW heat pump uses refrigerant to absorb heat from the outdoor air, or another ‘free’ heat source, and move it to the DHW tank.  Direct electric or natural gas energy sources can provide optional backup heating.  The efficiency of the heat pump is dependant on the type of refrigerant, the equipment selection and the heat source temperatures (ambient air for air-source heat pumps).  As technology continues to evolve, the ability to operate at a lower ambient air temperature is also improving.   Furthermore, refrigerant options today can include CO2 and low global warming potential refrigerants (the higher the score, the more damaging the product is believed to be for the environment).

Benefits of DHW heat pumps

DHW heat pumps are growing in popularity and becoming more readily available in the Canadian marketplace due to their ability to produce DHW at lower outdoor temperatures. Incentives for carbon reduction from Clean BC and utility companies have also made this type of system favorable for property owners and managers to integrate into their existing facilities.  With the recently announced federal carbon-tax increases to $170/tonne by 2030, upgrading to DHW pumps also helps organizations protect themselves from future increases to the operating costs of natural gas fired equipment. 

Key considerations

There are several key considerations when replacing your DHW system with heat pumps:

  1. What does the domestic hot water demand profile look like? 
    The Prism Engineering team can build a customized building profile that determines the equipment required to meet the building demand.
  2. What size is the existing electrical service? 
    The new equipment will require electrical power. The available electrical service and electrical panel capacity need to be reviewed as part of the design process.
  3. Is there physical space available for the heat pump system? 
    The heat pumps can be located outside on the roof, in landscaped areas on the ground floor, in parking garages or in mechanical rooms.  The space constraints and the ability to draw heat from the space (if inside) will define the equipment selection and design.
  4. What climate zone are the units going to be located in? 
    Although the units are designed to run at low ambient temperatures, some climate zones may require freezing weather packages. 
  5. Is redundancy required in the building? 
    Some buildings may require equipment redundancy which can impact the type of heat pump system chosen and the back up systems. 

Project experience 

Prism Engineering has been successful in working with our industry partners to evaluate and implement DHW heat pumps at numerous sites throughout BC.  The sites include buildings at Capilano University, Vancouver Community College, Interior Health, and BC Housing.

Our design for the Capilano University Sechelt Campus resulted in the elimination of natural gas to heat domestic hot water, providing 100% GHG savings for this end-use.

Curious to learn more? 
We would love to hear from you!  Connect with our Mechanical Team Lead, Stephen Kooiman, to discuss whether a DHW heat pump might be suitable for your next project.