Last week, we received two incredibly similar inquiries related to the ruling in ASHRAE 90.1 from table G3.1.1a that “All conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed.”

Here is a sample of the question we received:

I have a space in the proposed that is heated only. It has a peak heating load of 12 Btuh/SF, but the baseline peak is 20 Btuh/SF. In this climate zone, heating is defined as conditioned when the peak load is greater than 15 Btuh/sf. Since the proposed is not conditioned and the baseline is conditioned, do I treat the space as unconditioned, semi-heated, or conditioned? If it is conditioned, how do I proceed?

Response:

That's a funny issue. To be clear, I'm assuming you are using 90.1-2007. In terms of heating for your climate zone, conditioned is defined as >15 Btu/h·ft2. Semi-heated is always defined as >3.4 Btu/h·ft2. By the way, semi-heated = a minuscule amount of heating. I have scarcely seen or heard of semi-heated outside climate zones 1, 2, or 3. Of course, the setpoint could largely determine that.

Since you have mentioned 15 Btuh/sf, that means your model is in climate zone 4 or 5.

In any case, the conditioned vs unconditioned should be based on the proposed value, which in your case, is not conditioned nor is it unconditioned. Therefore it is semi-heated. However, because of the climate zone, it is very possible that any small changes will move you into the “conditioned” definition.

You have two choices:

1.   Model it as semi-heated, noting that any minuscule changes might make the space become conditioned.

2.   Model it as conditioned, which means adding cooling to the proposed. Option 1 might be the technically correct option, but you could stick to Option 2 to play it safe and LEED review should have no problem with this, unless for some strange reason it yields significant savings. There's other annoyances that arise from Option 1 because the baseline envelope actually changes to the semi-heated requirements from tables 5.5-1. This could work in your favor since those envelope conditions are “worse”, but it’s likely that this is a case of splitting hairs.

What to do:

Option 1)
If the space is unlikely to become conditioned, you could stick with Option 1 and model it as semi-heated in the baseline. In general, most changes requested by the LEED reviewer will RAISE the heating load.

Option 2)
You could be conservative and assume it is conditioned. Usually, all you need to do is keep things the way they are and add a single zone cooling unit to the baseline. Then you add the exact same cooling unit to the proposed, using the same efficiency and capacity.

To get really picky, you can also change the cooling setpoints on these fictitiously cooled spaces, provided the setpoints are the same in the proposed and baseline. I've heard that many people have adjusted these until it was 5 Btu/h·ft2 in cooling (making it conditioned, but just barely!). This makes the impact minor.

How would you handle this issue? Do you have a method of your own? Let me know what you think in the comments below.

I’d like to ask you the reader, what do you think I mean by the word ‘green’ in the title of this blog. I'd guess that most of you thought of multiple facets of green, but primarily thought of energy.

In the past decade, most conversations you have likely had about anything 'green' have had a large emphasis on energy. In some cases, it was probably the only topic in the conversation; energy consumption has become the cultural catch-all for being green. (even though energy consumption is only a piece of the green pie!)

Why has 'saving energy' become synonymous with “green”? This may sound like a trivial question but to put it in perspective, consider that twenty some years ago, the phrase ‘green’ was synonymous with “Don’t be a litterbug” and not using CFC’s. To say the least, perceptions have changed, and we have reached a perfect storm for promoting energy-efficiency. In my opinion, this perfect storm is a result of a number of socio-economic factors. Here are the top 3 on my list:

1) World-wide concern of climate change 

• This makes saving energy ‘cool’. 
• Saving energy is culturally relevant and marketable

2) Dramatic increase in energy consumption worldwide

• Increases the demand for cheap energy 
• Raises price of energy

3) Worldwide economic chaos

• The ROI for energy saving investments is easy to calculate and all but guaranteed. 
• Companies can use energy savings to increase their bottom line
• For remaining investors, higher energy prices coupled with higher market risks makes investing in energy savings more lucrative. 

Considering these 3 factors, when you are saving or conserving energy, you are doing the right thing, you are doing what is ‘cool’, and on top of all that you are being fiscally responsible while making an investment that will pay back (this ROI is one of the key arenas where energy-modeling is important!)

Now ask yourself, how often do your conscience, your reputation, and your pocketbook agree? Someone who is extremely frugal with energy is now deemed a hero where in the past they might have been called a cheapskate! 

“Energy is everything, but it’s not the only thing”

If you wish for humanity to continue on this worldwide trend and keep energy conservation in ‘the cool kids club’, remember that we can’t sacrifice luxury, comfort, or performance for energy efficiency.  To paraphrase a well known quote, “Energy is everything, but it’s not the only thing”. You see, while technically speaking energy is everything, including all matter and thought, it isn’t the only factor with respect to an energy efficient future. Cultural relevance is key. To keep energy efficiency relevant, remember that the energy efficient items need to be as good as or better than the items they replace.

Here at energy-models.com, our focus is on buildings, so let's consider some examples that MUST be considered alongside energy consumption, perhaps even consider these ABOVE energy consumption. It could be said that you design your building to save energy given these important factors:

Occupant health and wellness

This is largely attributed to providing adequate outdoor air, which can be energy expensive.

How do you offset this energy expense?

• Demand Control Ventilation

• Energy Recovery Wheels

• Airside Economizers and much more

Occupant Thermal Comfort

Thermal Comfort is not necessarily something you notice when you first walk into a new building, but it will be a primary factor if you spend much time in the building. Naturally, people do not like to feel cold in the winter and do not like to feel hot in the summer.

What can you do? 

• Install good windows, reducing cold drafts, and reducing direct solar glare
• Ensure proper airflow and zoning based on your airside system (this is done by quality building design)

Ease of Use

The building must be simpler or as simple to operate than a conventional building. Otherwise, the inevitable override will occur by the building operators. This will likely lead to a less comfortable building, and a building that uses more energy than intended. This would be devastating to the cause of building energy efficiency.

Solutions:

• Install integrated controls that require minimal programming
• Get to know the building operators and what they are comfortable with
• Provide ample training for building operators

As you can already see from this small subset of factors, building design is complicated. We’ve only touched on a small tip of the iceberg here and it only gets more complicated. A clever solution is needed. The number one tool in any building designer’s arsenal that can factor in so many variables is building energy simulation, with the emphasis naturally on building energy-modeling. 

Building Energy-modeling (BEM) can easily determine a return on investment, life cycle cost, energy savings and more. Many software packages can also do thermal comfort analysis, daylighting analysis, building load calculations and more. For many people, if it is just about energy-cost and emissions, you can run an energy model to determine if an upfront investment pays for itself. When you find the right setup for your building, you can go green and save some green.