October 16, 2012, by Josh Gentry

Geothermal: The Flexible HVAC Design

When we are beginning the design of new buildings there are a lot of things to consider when selecting the HVAC system type. These considerations range from sustainability to availability for local maintenance support, but by far the highest priority for 99% of projects is staying within budget. Staying within budget can be difficult to achieve with the exponential cost increase of more efficient and reliable HVAC options. Not only is there a high first cost for the more efficient system but, but there is a great discrepancy of cost on bid day. We have seen cost alone range from $1M to $2M for a building based on location and if contractors are local for the project. That is a huge dollar swing that could greatly impact your project and cause some major rethinking of the design of the building. This leads to the question: how can we fit all of our clients’ needs and give them the most “bang for their buck”?

This is where I think geothermal systems can offer a lot of benefits and flexibility. First, we can design the building to achieve the best performance for the amount of money we have available. This means starting with a full geothermal system, or a hybrid geothermal system that utilizes a fluid cooler. Utilizing a fluid cooler can greatly reduce the size of your well field and reduce your first cost. However, the fluid cooler will add cost to the life of the system for years to come with maintenance and replacement. This gives us as designers a scalable option that does not greatly impact the design of the internal systems. Let’s say for some unforeseen reason your client loses funding and has to cut cost on the project significantly. Geothermal can be scaled back further or removed all together and a fluid cooler and boiler could be used in place of the geothermal. This is a quick fix that will allow for a significant price drop on the HVAC equipment while still providing a system that meets the other needs of the client.