I spent last week at ACEEE’s Summer Study for Buildings, and one topic area I maximumly followed was energy codes and code compliance. In past years, I would rank codes and standards second to the bottom, just above lighting for my priorities. The reason for my sudden interest is the vaporizing gravy train of widgets, especially lighting and the need for other savings mechanisms. Why not code compliance?
States are updating energy codes willy nilly to the next rounds of ASHRAE 90.1 / International Energy Conservation Code. As the Church Lady used to say, “Isn’t that special?” The problem is the details, and as Church Lady also quips, “Could it be, SATAN?” [in the details?]
The common thread among any discussion of code compliance is that anyone who knows anything, including every single speaker who talked about it – and me – knows energy codes in new buildings are never met. Yet, we keep screwing down on the requirements to make ourselves feel better. Keep poppin’ the placebos, folks. Feel better yet?
Commercial new construction programs struggle to land substantial savings with fairy tale designs being measured against fairy tale codes. So, what is the solution? How about dealing with reality? This is related to the post from a couple weeks ago regarding realistic baselines for old buildings. How about realistic baselines – like buildings that are built – real ones that you can walk inside, touch, smell, see, and hear?
First, let’s define a couple things, at least the way I see them. What is the difference between a code and a standard? To me, a standard is equipment specifications – lumens per Watt, combustion efficiency, thermal efficiency, EER, and so on. These things are pretty well safe and certain as far as compliance goes.
What, then, is an energy code? To me, a code is the recipe for putting it all together. This includes design – duct and pipe sizing (for low pressure drop), controls (especially), and envelope things like tightness and insulation. There is no limit to system type and configuration, and that is usually done poorly. This is where energy codes fail badly.
So, what is the solution? The solution is twofold. Programs must:
- Disallow overly-complicated designs that are allowed by code.
- Deliver code compliance, plus.
One paper presented at ACEEE Summer Study for Buildings 2014 stole my thunder from my ACEEE Summer Study for Buildings 2012. Congratulations to that guy. He uttered the blasphemous statement that we need to ditch the outdated, insanely complicated, central variable air volume (VAV) system. One guy quoted a relatively simple control sequence for resetting hot water temperature – as an example of something that is complicated. I thought, you think that’s complicated, try to figure out how to set the minimum box positions for a VAV system.
In theory, it’s easier to become a neurosurgeon. In reality, the neurosurgeon knows what she is doing. The VAV system designer might as well pull numbers out of the air. They will be wrong anyway – and you know what they say about 10 engineers doing an energy calculation. Just assign them to a VAV system design. They would be as similar to the dogs in this poster, only less handsome.
A better analogy of commercially available HVAC system designs that meet code, from a design perspective, is an internal combustion engine versus a gas turbine. An internal combustion engine (like under your car hood) has hundreds of moving parts – linkages, pistons, valves, water pumps, oil pumps, heat exchangers, fans, and sensors galore. A gas turbine (jet engine) has one moving part – a compressor and the expansion turbine, on the same shaft.
The gas turbine of HVAC is the single-zone system. The internal combustion engine of HVAC is the crazy VAV system. With the central VAV system we have a gazillion pieces, parts, pumps, actuators, variable frequency drives, and constant sequencing and tweaking of valves, dampers, motor speeds, and so on. HVAC design with single-zone systems have nearly all binary control – on/off, open/close. Getting really wild with a design of single zone systems, an engineer might add a variable frequency drive to a ventilation fan or a pump.
Requiring single-zone systems gets us three quarters of the way to a decent performing building. Design, construction, and control mistakes are likely to have tiny impacts on energy performance compared to the central VAV system. Single zone deficiencies are easier to identify and fix because people are dealing with the binary stuff – controls and equipment – rather than whack-a-VAV-mole fashion. Push it in here, and it comes out over there.
Finally, get the heck out there and verify appropriate construction per program requirements. Utilities don’t want to be code enforcers. They don’t have to be code enforcers; just be program enforcers, as with every other program. This cannot be done (correctly) with a desk review only.
This is all wonderful Jeff, but what do savings and incentives look like? What is the baseline for the typical kludge building? – a worthy question. The answer would come from baseline and potential studies. Yes, I just beat those up last week. Focus these efforts on buildings that have been built in the last ten years – a random sample to collect system type, identify operating/control deficiencies, and especially collect/determine energy intensity in kWh and fossil fuel, typically natural gas, consumption per square foot – primary data collection – no self-report! This is the starting point.