Prerequisites/Mandatory Measures- 2
Minimum Points – 0
Maximum Points - 38

This category requires that the project improve the overall energy performance of a home by meeting or exceeding the performance of an Energy Star® labeled home, including third party inspections.

This Category is divided into 11 sub-categories, most of which contain prerequisites, and consequently the summary below will discuss together the prerequisites and possible additional points that may be earned in each sub-category.

Optimize Energy Performance. As a prerequisite, the home must meet the performance requirements of Energy Star® for Homes, which focuses on an energy efficient building envelope, efficient air distribution, energy efficient equipment for heating, cooling and hot water, efficient lighting and appliances, and includes third party inspections. Up to 34 points may be earned by exceeding the performance of Energy Star® for Homes based on a complicated mathematical calculation that effectively compares the Home Energy Rating System (HERS) Index to a specified number of LEED® points based on how well the home energy’s performance meets or exceeds the International Energy Conservation Code (IECC).

Insulation. As a prerequisite, insulation must be top notch and nearly eliminate air infiltration, leaks and thermal bridging. Specifically, the home must meet or exceed the R-value requirements listed in the IECC and insulation must be installed to meet “Grade II” specifications set by the National Home Energy Ratings Standards, which in plain English means that 90% of insulation defects, gaps around wiring and electrical outlets, vents, plumbing stacks etc. must be eliminated, wall insulation must be enclosed on all 6 sides (all 4 walls, floor and ceiling) and be in substantial contact with the sheathing material on at least one side (either interior or exterior) of the wall cavity (the space, or cavity, between the wall of the room and the exterior building wall). 

Two (2) points may be earned for enhanced insulation – insulation that exceeds the prerequisite R-value level by at least 5% and is installed to meet the more stringent Grade I specifications of the National Home Energy Ratings Standards.

Air infiltration. Minimize energy consumption due to uncontrolled air infiltration – leaks -- into and out of heated/cooled spaces. Air leakage tolerances under the LEED® for Homes guidelines for the building envelope (the building's roof, walls, windows, and doors -- the envelope, or separation, that controls the flow of energy between the interior and exterior of the building) depend on the climate zone in which the home is located, and must be tested by a Rater. Consult the Energy Star® website to look up your zone by map and/or zip code.

Houses leak air because of the difference between indoor and outdoor air pressure- hot air usually leaks outward from the top of the house and cold air usually seeps inward from the bottom of the structure. To measure leakage the house is subjected to a blower door test. The blower door test places a home under a known pressure by placing a large sealed fan in an exterior doorway that blows air out of the house to create a vacuum; in brownstones it may, instead, be optimal to instead do a “blower window test” which in essence places to large sealed fan in a window instead of a door, enabling the homeowner to test each floor individually simply by closing the ubiquitous doors to the stairwell, making it easier to pinpoint the exact location of leaks. Instruments then measure how much airflow is required to maintain the pressure difference between indoors and outdoors. The tighter the house, the less air the blower door must move to maintain a given pressure. Besides measuring the airtightness of the house, a blower door test also helps to pinpoint the location of specific air leaks using a smoke puffer or infrared imaging, or the simple old-fashioned way of feeling for draughts with a hand. The LEED® for Homes prerequisite for IECC climate zone 4 (where New York City is located), for example, is a maximum air leakage rating of 6.0 air changes per hour at 50 Pascals – a Pascal is a unit of measurement for air pressure, and the LEED® guidelines use the standard pressure difference of 50 Pascals between the inside and outside of the house. Reducing the air leakage to 4.25 times per hour earns 2 LEED® points, and to 2.5 times per hour earns 3 LEED® points.

Windows and Glass Doors. Maximize the energy performance of windows and glass doors by specifying and installing windows that meet certain minimum Energy Star® requirements for U-factor and SHGC (“Solar Heat Gain Coefficient”) factor depending on the climate zones in which the house is located.

Northern Climate (including NYC, Boston and Chicago): Select windows with a U-factor of 0.35 or less and any SHGC.

North/Central Climate (including Washington DC): Select windows with a U-factor of 0.40 or less and SHGC of .45 or less.

South/Central Climate (including San Francisco): Select windows with a U-factor of 0.40 or less and SHGC of .40 or less.

Southern Climate: Select windows with a U-factor of 0.55 or less and SHGC of .35 or less.

LEED® points can be earned by installing enhanced windows (2 points) or exceptional windows (3 points) that exceed by specified amounts the prerequisite standards for your climate zone. For example, triple-pane windows exceed the basic requirements and will also provide more sound insulation from busy city streets.

Heating and cooling distribution system must be optimized to minimize thermal bridges (when materials that are poor insulators come into contact, allowing heat to flow through the path created) and leaks. For forced air systems this means any leakage around ductwork must be outside the building envelope and ducts cannot be installed in exterior walls unless extra insulation criteria is met. For non-ducted HVAC systems (i.e. hydronic systems, meaning hot water heating and chilled water cooling) it means using a high-value insulation around pipes that are in unconditioned spaces. Up to 3 LEED® credits can be added if air leakage is reduced more than by the prerequisite amounts.

Space heating and cooling equipment must meet the following criteria:

(a) Equipment must reduce energy consumption by properly sizing the systems using calculations specified by ACCA Manual J (the Air Conditioning Contractors of America) or ASHRAE 2001 Handbook (American Society of Heating, Refrigeration and Air-conditioning Engineers). In other words, care must be taken not to oversize the systems by taking into account the excellent insulation, air leakage minimization, windows and other energy saving measures already put into place, and your mechanical engineer must be able to adjust the load calculations accordingly. Check back for Upcoming Articles on Heating and Cooling.   

(b) Equipment must be installed to meet the Energy Star® Builder Option Package which is a set of very specific performance requirements, based on climate zone, for central A/C and hot air systems, furnaces (gas, oil or propane), boilers (gas, oil or propane), and ground source heat pumps (geothermal) systems. A/C and air source heat pumps systems must meet a minimum Seasonal Energy Efficiency Ratio (SEER) level of 13 SEER and Heating Season Performance Factor (HSPF) level of 8.2 HSPF. Levels of 14 SEER and 15 SEER are considered enhanced levels that earn more points, however for the best performance (efficient and quiet) you may want to consider going as high as 18 SEER.

Fossil-fueled furnaces must meet a minimum Annual Fuel Utilization Efficiency (AFUE) level of 90 AFUE, with 92 and 94 AFUE considered enhanced levels that earn more points. Fossil-fueled boilers must meet a minimum AFUE level of 85, with 87 and 90 AFUE considered enhanced levels that earn more points, but we note that currently available high efficiency condensation boilers can be as high as 97% efficient. (Stay tuned for our Upcoming in-depth Article on heating systems.) Ground source heat pumps must meet specified Energy Efficiency Ratios (EER) for cooling and Coefficient of Performance (COP) ratios for heating. 

(c) Equipment must include installation of Energy Star® programmable thermostats except for heat pumps and hydronic systems.

Up to 4 LEED® credits may be earned by exceeding the prerequisite performance standards at specified levels.

Water Heating - No prerequisites; maximum 6 points. The goal is to reduce energy consumption associated with the hot water system, including the efficiency of the heater and the layout of the fixtures. There are specific requirements related to the amount of insulation on the hot water pipes, and the length of pipes from the hot water heater to the various branches depending on whether the plumbing system is a structured plumbing system which is based upon the recirculation of hot water, or a central manifold distribution system in which hot water enters a kind of small holding tank near the hot water heater from which many small lines go out directly to each hot water fixture in the home, or a compact design conventional system in which the hot water line runs as a main line (no holding tank) from the hot water heater then branches to the fixtures, and in most cases, the branches are short and the main hot water line is long.  This system, if not designed well, can lead to long waits for hot water the further the fixture is from the hot water heater, and a lot of wasted cold water flows down the drain as the user waits for the hot water, a common problem in brownstones where water has to travel vertically several floors from a single heater in the basement.  Refer to our Articles Water Heating - Understanding Water-Saving and Energy-Saving Measures and Water Conservation --A Holistic Approach that Saves Water and Energy.  Additional points may also be earned depending on the efficiency rating of the chosen equipment, and the use of solar hot water equipment earns more points.

Lighting. The goal is to reduce energy consumption associated with interior and exterior lighting.

Prerequisites: Install at least four Energy Star® labeled light fixtures or Energy Star® labeled compact fluorescent lights (CFLs) in high-use areas such as the kitchen, living room, family room and hallways. Up to 3 LEED® points can be earned by installing more Energy Star® labeled fixtures or CFLs indoors, and either motion sensors or integrated photovoltaic cells outdoors, or by installing the Energy Star® Advanced Lighting Package which is comprised of a minimum 60% Energy Star® hard-wired fixtures and 100% Energy Star® ceiling fans, or 80% Energy Star® labeled lamps or Energy Star® CFLs.

Improving lighting efficiency can also further reduce energy consumption by reducing cooling loads.

Appliances. The goal is to reduce energy consumed by appliances. There are no prerequisites. Up to a total of 3 points can be earned for high-efficiency appliances: up to 2 points for refrigerators, ceiling fans, dishwashers and clothes washers, and an additional point can be earned if the clothes washer also meets water-efficiency standards set by Energy Star® being the MEF (Modified Energy Factor) of at least 2.0 and a water factor of less than 5.5.

Renewable Energy. Up to 10 points. The goal is to reduce consumption of nonrenewable energy sources by encouraging the installation and operation of renewable electric generation systems. Energy modeling must be done to estimate the energy supplied by the renewable system and the annual reference electrical load. There are no prerequisites, and up to 10 points may be earned, 1 point for every 3% of the annual reference electrical load met by the renewable system. This measure contemplates solar, wind and passive solar, but not solar hot water which is covered in a separate area of the guidelines. Stay tuned for our Upcoming Article on Renewable Energy in an Urban Environment.

Air conditioning refrigerant systems must be selected and tested to ensure performance and to minimize ozone depletion and global warming. Prerequisites involve providing proof of proper “refrigerant charge”, which means it is necessary to have the correct amount of refrigerant in the system otherwise A/C systems can use up to 30% more energy. One point can be earned for a cooling system that does not use refrigerants at all (such as proper ventilation, dehumidifiers and whole-house fans), or has an HVAC system that uses a non-HCFC (hydrochlorofluorocarbon) refrigerant which is a substance that is known to cause depletion of the ozone layer. Currently the EPA limits the amount of HCFC that may be produced, and intends to prohibit its use by 2030, and the LEED® for Homes guidelines contemplate use of the substitute refrigerant R-410A. Alternatively, another refrigerant can be used if it passes a complicated mathematical analysis of its characteristics based on its ozone depletion potential, its global warming potential, its leakage rate, the refrigerant charge and the equipment life.

What does this mean for brownstone and row-house renovation: The guidelines can be generally applied to a brownstone because efforts to create a tight building envelope, efficient heating, cooling and water heating systems, and low-energy lighting have universal application, however the choices to be made in each category may be dictated by the nature of a brownstone. For example, it may be more practical to use blown-in insulation rather than blanket roll insulation if you’ve got existing walls with the result that you may need to deal with the uncertainty of ending up with a few pockets of air in the wall where the insulation cannot make its way through the uneven wood or metal lathe and plaster; or, for instance, the type of hot water heating system you choose may be dictated somewhat by pre-existing pipe arrangement, etc. We will be analyzing the individual aspects of these elements in separate, in-depth Articles.