While working on a building’s energy system, it is difficult to refrain from observing other systems. It is often necessary to understand the building as a group of systems working together (or against each other) to implement a proper design. For example, re-sizing a chiller is dependent upon understanding the hot/cold deck arrangement on the multi-zone air handler it serves. The original design requires the heating plant to operate in order to have heat available on the hot deck. During the summer this is not required, but the system remains operational. If any zone is too cold, the dampers modulate, and the supply air is heated. The only path for the air is to be heated, or cooled.
If heating and cooling work against each other, is there a way to minimize (if not prevent) this from occurring?
How can a new control system interact with the old without taking it over?
When is it appropriate to heat and cool at the same time?
Selective retrofits are difficult because from the retrofit designer’s perspective all good ideas should be implemented to maximize the benefit of the new system, but increasing project time and costs deter this from being realized.
So before a complete over-haul is implemented, evaluate what can be done with the existing equipment and when it should be done, but these changes shouldn’t wait to be highlighted by the next proactive engineer who walks through the mechanical room. One of EEI’s roles is to re-design energy systems, and the most common no-cost opportunity is to simply turn the equipment off – especially fans and pumps. Mechanical rooms are hidden from the public, and a pump’s purpose can be hidden from building operators. A pump could remain operational until it breaks, and the symptom is traced back to its failure. Maintenance staff are often in a position of being overwhelmed with occupant complaints and maintenance emergencies, they can’t understand the entire system and be proactive to turn off equipment at the right time.
A system cannot be set, then forgotten. Each season produces unique operating conditions, and should not operate the same way as the previous season, or previous year. This produces an opportunity to evaluate your energy systems on a quarterly basis. Questions to ask may include:
Did the heating plant perform as predicted in the winter?
Where were occupants uncomfortable in the spring and fall?
Did the retrofit HVAC equipment perform as expected?
How did the building perform against its benchmark?
What set points can be changed?
Who is responsible for implementing these changes? How can we track success?
A building operator cannot address these questions single-handedly. Their workload can already be beyond their abilities, so capacity must be added to enable change. Next, a committee of knowledgeable staff should regularly meet to help evaluate progress. This can be something at the macro level with a steering committee, or at a micro level with a group of people equipped with measurement devices.
If this issue is to be rectified, more attention must be paid to the systems you rely on. They may remain hidden from the occupants, but reducing equity and operating costs will produce real results.
View a case study by clicking the link below.
Dave Ferguson, C.Tech, BA, G3