According to the NYC Urban Green Council, around 85% of city buildings will still stand in 2050. Considering that the city has an ambitious emissions reduction target of 80% for that year, existing buildings will require significant upgrades to reduce their environmental footprint. New constructions normally achieve superior energy performance compared with retrofitted buildings, but demolishing and rebuilding an existing property is extremely expensive and unfeasible in most cases.
A building retrofit that is well planned and executed can cut down building energy consumption by around 50%, while emissions decrease by 65%. A new construction achieves an extra 5-10% of energy efficiency, but this is a small gain compared with the cost of rebuilding it from zero, not to mention the environmental impact of demolishing the old building. Several decades may pass before the marginal performance gains of a new construction make up for the environmental and financial impact.
Like with any engineering project, an unplanned approach is unlikely to yield good results in a building retrofit. The first step is to assess the condition of your property and identify key areas of opportunity. These can then be analyzed individually in terms of technical and financial viability, creating an investment plan to retrofit the building.
What is the Current Condition of the Building?
There are two complementary ways to assess the performance of your building: benchmarking tells you how well it performs compared with other properties of similar characteristics, while energy audits can give a detailed breakdown of energy consumption, making it easier to identify the most promising building upgrades. The ENERGY STAR score from the US Environmental Protection Agency provides an excellent tool for buildings to compare their performance with similar buildings from throughout the country - buildings with a score of 75 or more earn ENERGY STAR certification, where the maximum value is 100. Consider that in NYC, buildings above certain size thresholds are required by law to benchmark their energy use (Local Law 84) and perform energy audits every 10 years (Local Law 87).
Proposing energy efficiency measures without knowing the actual condition of a building is basically a trial-and-error approach, and property owners are strongly advised against it. On the other hand, benchmarking allows property owners to set realistic targets, while energy audits provide a feasibility study. Energy audits may also reveal opportunities for recommissioning: minor adjustments to operating parameters and controls, along with simple reparations, which yield performance improvements at minimal cost.
When an energy audit is completed, the total cost of all the measures proposed may be too high for building owners to assume at once. If this is the case, a set of measures may be given priority due to their ease of implementation or high financial return. Upgrades to electrical systems tend to offer the highest return on investment due to the high cost of electricity, but upgrades to combustion-based appliances tend to eliminate the most emissions. Keep in mind that some measures may be mandatory according to NYC building codes and legislation. For example, all buildings using #4 heating oil must convert to #2 or a cleaner option by 2030, and all lighting systems in buildings covered by Local Law 88 must be upgraded to meet the NYC Energy Conservation Code by 2025.
Financial analysis of building upgrades also provides a basis for investment decisions. Businesses often use financing for major building upgrades, to minimize the impact on their cash flow. Building upgrades that have operating savings higher than debt service are especially attractive, since they can pay for their own cost.
Implementing the Suggested Building Upgrades
NYC has a broad range of building codes, and the ones that apply depend on the type of project. The technical requirements are demanding across the board, but especially in the case of fire protection systems and combustion-based appliances. The best recommendation is to work with a qualified engineering firm throughout the entire process, from design to commissioning.
Many property owners decide to start with lighting upgrades, for many reasons outlined below. In fact, the US EPA recommends these building upgrades as a first step in any major building retrofit.
The procedure is simple and less disruptive than other upgrades, while offering a payback period of just a few years, and in certain cases less than one year.
Lighting upgrades may be eligible for cash rebates from Con Edison, further increasing their financial return. Depending on building characteristics and location, some lighting upgrades may be available for free.
Lighting upgrades do not depend on other building systems, and in turn they can achieve synergy with subsequent ones. For example, LED lighting is easier to integrate with building controls, and also reduces the design load for air-conditioning upgrades.
Compared with other building upgrades, lighting retrofits are relatively simple to design and approve.
After lighting upgrades, the recommendation is to proceed with measures that reduce heating and cooling loads. Financial analysis is very important here, since these measures tend to show a broad variation in cost. For example, caulking and weatherstripping are quick and affordable, while upgrading to high-performance windows can require a significant capital and time commitment.
A logical next step is HVAC, since the previous upgrades tend to reduce its load. As a result, the new equipment can be specified with a higher efficiency and a lower capacity, boosting the savings achieved. From the technical standpoint, it makes sense to upgrade ventilation systems first: many ventilation systems in NYC are oversized, increasing the required heating and cooling capacity due to excessive airflow. With an optimally-sized ventilation system, adequate room temperatures can be achieved with less heating and cooling. In addition to optimizing capacity, ventilation systems can be equipped with energy recovery to further reduce heating and cooling loads.
Working with qualified design professionals is important throughout the entire building upgrade process, but the stakes tend to be higher once property managers are dealing with HVAC. These upgrades are expensive and disruptive, but can also yield significant performance improvements. However, for this same reason it is very important to get them right - HVAC systems involve a complex interaction between many components that cannot be analyzed in isolation.
At Nearby EngineersNew York Engineers , we search for simple, eloquent solutions to complex problems. We minimize construction costs by eliminating the extraneous and focusing on the overall efficiency for the most streamlined designs.