6 Energy Efficiency Tips from the NYC Urban Green Council

Building owners and equipment suppliers don’t always use the same vocabulary when discussing engineering projects, and this results in missed opportunities to improve energy efficiency. According to the NYC Urban Green Council, building owners often have their problem areas identified, but are unaware of the existing solutions. As a result, technology suppliers conclude that demand for energy-efficient products is low or nonexistent. Improved communication between both parties could bring many innovative projects in NYC.

To help solve this issue, the Urban Green Council carried out a study of the energy efficiency market in NYC. They identified six types of building upgrades that could have a high demand, but where few projects are materialized due to miscommunication between users and suppliers.

Note that the savings values provided above are percentages of total building consumption, not just the building system being upgraded.

1) Packaged Condensing Boilers for Combined Space Heating and Hot Water

A packaged unit combining space heating and domestic hot water would be very attractive for NYC property owners, according to the Urban Green Council. In simple terms, exhaust heat from the space heating boiler is recovered for the domestic hot water (DHW) system, reducing total consumption.

The concept is viable with conventional condensing boilers, but installation is very complex because a heat exchanger is required. If equipment suppliers offered an integrated solution, the installation would be simplified greatly. This also reduces the number of man-hours required, making the project faster and more affordable.

2) Split-Type Heat Pumps Designed to Replace PTACs

Packaged terminal air conditioners (PTAC) are often chosen in NYC buildings for their ease of installation and lower upfront cost that other AC systems. However, their long term ownership cost is very high:

• PTACs interrupt the building envelope, increasing summer heat gain and winter heat loss.
• They also have a low efficiency themselves.

Split-type air-source heat pumps could be designed to fit into the same spaces as PTACs, while adding improved insulation and air tightness. Ventilation can be built-in as well, achieving a complete HVAC solution that is easy to retrofit.

3) High-Efficiency and Modular Air Conditioners

Commercial spaces tend to have very different operating schedules, and deploying a central chiller plant is impractical in many cases. Direct expansion units are more common for this reason, but they come with a lower efficiency.

Compressor designs for chillers have achieved impressive efficiency, but the concept is rarely deployed at the smaller scale of commercial spaces (typically below 20 tons). Modular systems with newer compressor models would achieve savings of around 30% according to the Urban Green Council.

4) Insulated Wrap for Balconies and Floor Slabs

Heat loss occurs through balconies and floor slabs, since they cause an interruption in the building envelope. The negative effect of one slab is small, but it becomes significant when you consider an entire building.

This issue can be solved by applying insulated wrap around the edges of balconies and slabs. In addition, this is a versatile solution that works in both new constructions and existing buildings.

5) Low-Conductivity Shelf Angles for Masonry Walls

Shelf angles are the structural elements that attach masonry walls to the main building structure. However, conventional shelf angles are highly conductive because they are made of steel, contributing to unwanted heat transfer across the building envelope. Newer composite materials can accomplish the same function without the heat loss, as long as they offer the same structural and fire resistance properties of conventional shelf angles.

6) Advanced Curtain Walls

Curtain walls are common in newer NYC buildings, but their envelope performance is very poor. In many cases, simple brick and mortar walls provide better insulation. Buildings with curtain walls often have efficient mechanical and electrical systems, but optimal performance is not achieved because of the poor thermal envelope.

High-performance curtain walls are already standardized and widely used in other parts of the world, such as Europe, but the concept has been slow to enter the US market. These versions of curtain walls have integrated insulation measures, achieving synergy with efficient space heating and cooling systems.

Conclusion

There are many untapped opportunities for energy efficiency measures in NYC, but miscommunication between suppliers and property owners hold them back. Getting an energy audit from a qualified engineering company is highly recommended to identify the best upgrades for your property.