Party Walls

Did you know that there are two pathways for earning Passive House certification? There’s Passive House International (PHI) and Passive House Institute US (PHIUS). Using an energy modeling software, both programs evaluate a building based on a variety of factors. Despite the misleading moniker, certification is not limited to just housing. In fact, building types from residential and commercial high-rises to industrial factories have earned Passive House certification around the globe. However, the two certification programs are run by separate institutions, using different energy modeling software and standards. However, both ultimately maintain the shared goal for high performance, low energy buildings.

Historically, around 2013, the PHIUS organization developed a new standard called PHIUS+ 2015 with a climate-specific approach and an alternate modeling software. Starting in March 2019, PHIUS projects will be held to updated requirements under the PHIUS+ 2018 program.

PHI also offers project and climate specific cooling demand thresholds, having previously begun offering alternate certification options in 2015. Additionally, PHI created a program called EnerPHit to provide more flexibility for retrofits. PHI recognizes buildings that exceed its standard certification by offering Plus and Premium certification, as well as a Low Energy Building certification pathway for projects that are near PH efficiency.

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It has been clear for some time that energy codes are on course to require carbon-free buildings by 2030. Adoption at the local level will see some areas of the country getting there even sooner. For example, California has set net zero goals for its residential code by 2020. These developments have accelerated the debate about the effectiveness of energy modeling versus performance-based approaches to compliance.

Let’s start with energy modeling, where change is coming for the better. In the past, the energy modeling community has been required to continuously respond to energy code cycle updates with new baseline models. That is, the bar for uncovering savings would be increased each and every time a new energy code was adopted. Following a code update, program staff and the energy modeling community would have to go through another learning curve to determine where to set a new bar and how to model the changes. (more…)

Steam pressure gets a disproportionate amount of attention. That’s partially due to the common, but not necessarily true idea that higher pressure equals more fuel use. Remember, it’s not the steam’s pressure that heats the building; it’s the steam’s heat energy. In fact, you can heat a building with 0 psig steam. You can even heat a building with a boiler that’s too small and never builds positive pressure. You can’t do it well, but you can do it.

System Operation

Thanks to the law of conservation of energy, we know that energy cannot be created or destroyed — it can only be altered from one form to another. In a steam heating system, the flow of energy goes like this:

1. The boiler transfers Btus from the fuel to the steam (energy input).
2. The steam transfers those Btus to the rooms.
3. The rooms transfer those Btus to the outdoors (heat loss, aka the load).

It’s important to keep this energy flow in mind because they are linked and self-equalizing. If the energy input exceeds the heat loss, the building temperature will increase, which, in turn, increases the heat loss. And, a building’s heat loss depends on the temperature difference between inside and outside and the amount of air transfer occurring. So, the best way to keep the heat loss down is to keep the indoor temperatures as low as possible, and keep the windows closed. Furthermore, in an apartment building, the coldest room drives the load in any steam-heated building and the Super needs to send enough heat around to satisfy the hardest-to-heat apartment.

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Sometimes a significant source of energy inefficiency in a building can be hiding in a place difficult to detect. In some buildings, a single transformer can have a substantial impact on electrical consumption.

Some Background

Transformers are responsible for stepping the incoming voltage to a building up or down depending on the design, intended use, or connected equipment. A standard electrical socket in a US home or office will deliver 110-120 volts AC. Some appliances require 240 V instead. Large mechanical equipment, such as the air handling units, distribution pumps and chillers found in commercial or multifamily buildings may require 460 V. In buildings where the incoming voltage from the utility does not match the voltage required by connected equipment, a transformer is used to deliver the necessary voltage. The voltage entering the transformer is called the primary voltage and the voltage delivered by the transformer to the facility’s equipment is called the secondary voltage.

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New York City has established high goals for CO₂ reductions as part of the 80 x 50 plan enacted under Mayor de Blasio’s administration. In short, NYC aims to reduce its CO₂ production by at least 80% by 2050 (from a 2005 baseline). This requires vast energy conservation and renewable energy production proliferation across the city’s energy, transportation, waste management, and building sectors. Buildings themselves account for 68% of current CO₂ production in the City, and as such have the largest reduction targets¹. Goals can only be met by implementing repeatable and scalable scopes of work in coordination with policy updates and improvements in other energy sectors. To better understand the efficacy of these moderate improvements on overall energy consumption, we’ve analyzed the results from a recent portfolio rehabilitation. These findings help us to create a map of where we need to go in order to approach 80 X 50.

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