<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=448100748896598&amp;ev=PageView&amp;noscript=1">
⚠ We're here to serve you during the COVID-19 pandemic. Click here to learn how >>
Regency Lighting logo
  • Shop Products
    • Light Bulbs
    • Ballasts & Batteries
    • Batteries
    • Electrical
    • Fixtures
    • Specialty
    • Business Account Signup
  • Services
    • Problems We Solve
    • Design Consulting
    • Construction Services
    • Replacement Products
    • Lighting Maintenance
    • Retrofit Management
    • Sustainable Recycling
    • Product Lines
    • Client Success Stories
  • Resources
    • Lighting Blog
    • Total Cost of Lighting
    • Energy Savings Calculator
    • Lighting Glossary
    • Title 24
      • Title 24 FAQ & Glossary
      • Does Title 24 Apply to Me?
  • About Us
    • Culture
    • Values
    • Causes
    • History
    • Team Success Stories
    • Leadership
      • Ron Regenstreif
      • Mike Goldstone
      • Scott Anderson
      • Judah Regenstreif
      • Ron Pilner
      • Hoon Kim
    • Careers
    • Regency Lighting News
    • Event and Social Photos
    • Regency Branding
  • Contact Us
    • Credit Application
    • Apply for Tax Exemption
    • Contractor Network
    • Office Locations
  • Store Login

Start typing and press Enter to search

bg.jpg

Lighting Insights Blog

Lighting Insights from Regency Lighting Regency Lighting Logo

< Back to blog

How to calculate HVAC energy savings from lighting: A step-by-step guide

Posted by Chris Radosta on Jul 5, 2017 9:20:00 AM
Find me on:
LinkedIn
print
  • Tweet

image for How to calculate HVAC energy savings from lighting: A step-by-step guide article 

This is the second in our series of articles meant to take the mystery out of savings and payback calculations for lighting. From designers to engineers to executives, lighting projects are more commonly cross-functional decisions. 

This article focuses on one of the least-covered questions on savings calculations for lighting projects: How can a lighting retrofit save you money on HVAC costs?

While this may seem far-fetched, our detailed, step-by-step instructions will help you calculate your potential savings so you can determine for yourself if you think it is appropriate to factor it into your savings calculations. For starters, this only applies to lighting retrofit projects done in a space that uses air conditioning.


Looking for more simple, "gut check" calculations? Use our Energy Savings Calculator to get started. 

Lighting calculator: calculate energy savings on lighting projects


The principle behind HVAC energy savings from lighting

Traditional lighting products, like incandescent and halogen bulbs, put off a ton of heat. In fact, they are more efficient at producing heat through that glowing hot filament than light. Each watt of light output produces heat in your facility that has to be dealt with, and in summer months, that takes extra energy.

There are several ways to calculate the HVAC savings from lower wattage lighting, but the simplest is a “rule of thumb” standard developed by ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers). Their guideline states that 30 to 35 watts of cooling is required to offset the heat output for every 100 watts used to light a space (we will meet in the middle and use 33 watts or 0.33 for our example below).

For our example, we will continue with the example we started with in our last article –– "How to calculate energy savings for lighting only." You are replacing a 90 watt PAR 38 bulb with a 14 watt LED PAR 38 that operates 12 hours a day and 360 days per year. Let’s get started!

Step 1: Gather your facts

You will need to pull together the following items before we dive into the calculations.

  • Total annual energy savings: In this case, the annual savings is 328 kWh (see Step 4 in “How to calculate energy savings for lighting only”)

  • Months of cooling: Estimate the number of months that your location(s) operate air conditioning. In this case, let’s assume we are located in New York City, which averages about 4.6 months of cooling per year. We use this reference from the U.S. Navy to figure out the months of cooling.

  • Electricity rate: This can be tricky depending on the utility rate you are paying, but a reasonable national average is $0.10/kWh to $0.14/kWh. For our example, we will use $0.12/kWh.

Need a kilowatt primer? We explain here: 'kW vs. kWh: How much energy is my lighting using?'

Step 2: Calculate percentage of the year when cooling is running

Remember that we only want to calculate the heat reduction savings during months when the cooling system is actually operating.

   Months of Cooling
÷ 12 Months

= % of Year when Cooling Runs

Our Example:
   4.6 Months of Cooling
÷ 12 Months

= 38.33% of the Year Cooling is Operating

Step 3: Calculate energy savings from reduced HVAC load

Now that we know we’re running cooling for a little more than a third of the year, we can figure out how much energy would be used to cool the space just to offset the higher-wattage lighting.

   Annual Energy Savings from Lighting
x % of the Year When Cooling Runs
x ASHRAE Rule

= Energy Savings from Reduced HVAC Load

Our Example:
   328 kWh
x 38.33% of Cooling Time
x .33 ASHRAE Rule

= 41.49 kWh of HVAC Energy Savings per Year

Step 4: Calculate dollar savings from reduced HVAC load

Now that we know how much electricity we are saving, we need to see how it translates to real dollars.

   HVAC Energy Savings per Year
x Electricity Rate

= Total Dollar Savings (from HVAC)

Our Example:
   41.49 kWh Saved
x $0.12/kWh

= $4.97 Saved per Bulb per Year

This may seem like a small amount of energy, but scale this across hundreds or thousands of sockets across your company and you will quickly reach significant numbers. Some of our clients still prefer to leave this factor out of their payback estimates for the sake of being conservative, but it’s important that you know the full impact of a lighting retrofit project.

Ultim

Additional Resources:

  • How to Calculate Return on Investment (ROI) and Payback for Your Lighting Project
  • How to Calculate Labor Savings from Long-Life Lighting
  • How to Calculate Material Savings from Long-Life Lighting
  • How to Calculate Energy Savings for Lighting Only
  • The Plain Truth Behind Lighting Retrofit Savings

Topics: Savings, Payback, & ROI, Lighting maintenance, Energy efficiency, Hotel lighting, Education facility, Energy savings, Multifamily lighting, Commercial office lighting

Related posts

3 steps to retrofit from T12 to LED
3 steps to retrofit from T12 to LED
Solving for color consistency in LED lighting
Solving for color consistency in LED lighting
How to recycle fluorescent lighting and electronic waste
How to recycle fluorescent lighting and electronic waste

Have a comment?

Shop Regency Lighting

Sign up for a Regency Lighting Business Account

Recent articles

View all posts >
 

Articles by topic

  • LED (63)
  • Energy efficiency (42)
  • LED retrofit (30)
  • Commercial office lighting (29)
  • Fluorescent light (27)
  • Energy savings (26)
  • Retail Lighting (26)
  • COVID-19 (25)
  • Savings, Payback, & ROI (24)
  • Parking Garage Lighting (22)
  • Lighting maintenance (21)
  • Restaurant Lighting (21)
  • Lighting 101 (20)
  • Lighting design (20)
  • Hotel lighting (19)
  • Germicidal UV light (18)
  • Multifamily lighting (17)
  • Product Comparison (17)
  • Inside the Industry (16)
  • Project Management (14)
  • Education facility (11)
  • FAQs (11)
  • Incandescent lighting (11)
  • Lighting rebates (11)
  • HID (10)
  • Hospital lighting (10)
  • Inside Regency (9)
  • Lighting technology (9)
  • Ballast (8)
  • Movie theater lighting (8)
  • Lighting tidbits (7)
  • CRI (6)
  • California Energy Code (6)
  • Color temperature (6)
  • Title 24 (6)
  • Healthcare lighting (5)
  • LED dimming (5)
  • T12 (5)
  • Warehouse lighting (5)
  • Building inspections (4)
  • Code enforcement (4)
  • Lighting as a service (4)
  • CFL (3)
  • Energy Star certification (3)
  • LED lifespan (3)
  • Light bulb part numbers (3)
  • Lighting controls (3)
  • Manufacturer warranty (3)
  • Wattage (3)
  • Charity highlight (2)
  • DLC listed (2)
  • Hallway lighting (2)
  • CCT (1)
  • ETL listed (1)
  • Energy code (1)
  • Halogen (1)
see all

Quick Links

  • Insights Lighting Blog
  • Energy Savings Calculator
  • Lighting Glossary
  • Product Lines
  • Client Success Stories
  • Our Values
  • Careers
  • Mobile Store Login

Lighting Insights

RL Headquarters

Regency Lighting 
9261 Jordan Avenue
Chatsworth, CA 91311
Phone: +1-800-284-2024
Fax: +1-800-763-7636
Send us a message.

rl-us-map-locations-web-small-r

National Lighting Distributor since 1983

Find the location nearest you.

 

Regency Lighting Logo Website

© Regency Lighting
All Rights Reserved.

  • Problems We Solve
  • Products + Services
  • Lighting Resources
  • About Us
  • Contact Us
  • Site Map
Regency Lighting Logo Website

© Regency Lighting
All Rights Reserved.

  • Problems We Solve
  • Products + Services
  • Lighting Resources
  • About Us
  • Contact Us
  • Site Map