Energy expenses represent a significant portion of building ownership costs in New York City. Electricity prices are among the highest in the country, and although most space heating and domestic hot water systems use fuel combustion, they also result in high expenses due to the sheer demand for heat in NYC buildings.

Heating, ventilation and air conditioning (HVAC) systems normally account for over 40% of energy usage in NYC office buildings, and over 60% of energy usage in multifamily buildings. Therefore, improvements to HVAC installations can yield a significant reduction in energy costs. In addition, HVAC consulting services can help you address other issues such as:

  1. Deficient HVAC performance
    Excessive heating or cooling, a constantly-changing temperature or air drafts from the ventilation system, to name a few examples.

  2. Deficient Indoor Air Quality (IAQ)
    HVAC systems that are not properly designed also suffer from poor humidity and air pollutant control.

  3. High Greenhouse Gas Emissions from a Building
    Saving electricity reduces emissions indirectly, since that power could have been generated from fossil fuels. Upgrades for combustion-based heating equipment also reduce emissions if you switch to a less polluting heat source or if you improve system efficiency.

  4. Vibration and Noise
    Since HVAC systems include some of the largest pieces of equipment in buildings, they can cause vibration and noise issues.

Keep in mind that HVAC upgrades are subject to the NYC Energy Conservation Code. However, since the goal is to improve HVAC performance in the first place, the requirements of the energy code are actually helpful as a roadmap.


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Improving HVAC Performance

A well-designed HVAC installation delivers the right conditions for building interiors to be used by humans: air temperature, water temperature, airflow speed and indoor air renovation. When either of these variables is not controlled properly, comfort and health issues normally arise. If your building has an old steam radiator system, it is probably oversized because these installations were originally designed for the heating load with open windows; airtight buildings are a relatively modern trend.

HVAC consulting engineers can inspect your existing equipment and propose upgrades to improve performance. Three main types of measures are typically proposed, and they are summarized in the following table:

HVAC UPGRADE MEASURE

DESCRIPTION

Recommissioning

Recommissioning consists of simple and low-cost adjustments for HVAC components that may be configured incorrectly or poorly calibrated. Recommissioning also includes minor reparations and component replacements. When a building has never been recommissioned before, the term “retrocommissioning” is used. The process tends to be more labor-intensive because it hasn’t been performed before.

Equipment upgrades

A straightforward measure: old and wasteful equipment is replaced with newer and more efficient units. If the original equipment had the wrong capacity, this is a great opportunity to correct it.

Automatic controls

As a complement to installing more efficient equipment, automatic controls can be deployed to ensure it is used optimally. Modern chillers and boilers typically have these controls built-in and they must only be configured. Other equipment in HVAC installations, such as hydronic pumping systems or air handlers, can use external control devices. For example, motor-driven equipment can be equipped with variable speed drives to match air or water flow with demand.

These upgrades have the same goal: specifying HVAC installations that deliver suitable indoor conditions for humans, while optimizing the operating cost. You can also expect a reduction in maintenance expenses, for the simple reason that the new equipment is not worn down.

Improving Indoor Air Quality (IAQ)

We tend to focus on energy savings when improving HVAC systems, but delivering indoor air quality is also very important. The consequences of poor IAQ can range from minor discomfort to health issues; for example, some air pollutants can cause allergies or asthma attacks if the ventilation system does not remove them effectively from indoor air.

Consider that pollutant control is only one aspect of indoor air quality. Monitoring and controlling humidity is also very important:

  • Excessive humidity stimulates the reproduction of mold, dust mites, bacteria and viruses. All are detrimental for IAQ.
  • On the other hand, excessively dry indoor air can irritate the skin and airways. Dryness also favors some viruses, and dust stays suspended in the air for a longer time; humidity binds dust particles together and with surfaces, making them easier to clean.

The US Environmental Protection Agency recommends keeping relative humidity between 30% and 50% to provide the best indoor environment for humans. Although there are both air humidifiers and dehumidifiers in the market, they tend to consume a lot of energy. For the best results and energy efficiency, humidity control should be engineered into the HVAC installation.

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Adequate venting is extremely important for combustion-based appliances. While main indoor air pollutants cause irritation or allergies, combustion exhaust contains substances that are actually poisonous, such as carbon monoxide.

Reducing the Carbon Footprint of a Building

The NYC government has established the ambitious goal of reducing greenhouse gas emissions by 80% by 2050, taking 2005 as a baseline. The city infrastructure will require numerous upgrades to achieve this goal, and combustion-based heating systems account for a large fraction of emissions in NYC.

An HVAC upgrade that typically saves cash while lowering emissions is a fuel conversion for space heating and domestic hot water systems. If your heating equipment still runs with heating oil, converting to natural gas can reduce emissions and you no longer have to rely on oil delivery, since natural gas is delivered through underground piping. In fact, depending on what type of heating oil you have, an upgrade may be mandatory - No. 6 fuel oil is already banned due to its high emissions, and No. 4 fuel oil must be phased out by 2030.

Controlling Noise and Vibration in HVAC Equipment

HVAC installations involve plenty of moving machinery, including compressors, pumps and fans. If these pieces of equipment lack the right support, they can generate vibration that propagates through other building elements. For instance, an air handling unit with poor vibration control can affect the air ducts, the ceiling and even lighting fixtures, which also causes noise.

When major HVAC equipment is properly sized and supported, vibration issues are minimized. Although it is generally impossible to eliminate noise and vibration completely, they stop being an issue if they can be reduced to a point where they do not affect other building systems and are not perceived by occupants.

Final Recommendations

Consider that HVAC systems are technically complex and subject to many building code requirements. There are many system configurations available, which means there is often more than one viable solution for a specific application, but variety can also lead to confusion. Working with qualified HVAC consulting engineers makes sure you get high performance and energy efficiency at an optimal cost.

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