FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

Efficincy of Zoned HVAC

GSchooter | Posted in Energy, Heating & Insulation on July 4, 2002 07:21am

I have just moved into a new House in December 2001. House has 2450 sq ft, of which 700 sq ft is on 2nd floor, and there is an open Stairwell. I have a single Nat. Gas Forced Air Heating + Cooling System with two Zones. The house has 2×6 walls with blown R-23 insulation and ceilings with R-48 insulation. As expected – – Hot air rises. Last winter, the 1rst floor thermostat essentially controlled the heat due to an increase of 1 degree from the 1rst to the 2nd floor due to the open stairwell. I was O.K. with this. Likewise, this summer, the 2nd floor thermostat controls the cooling cycle due to a 2 degree difference from up to down.

Since my Zoning system only allows one Zone to operate at a time, the 2nd floor calls for cooling first since it heats up first and runs until its cooling needs are complete. All the cooling power of my system seems to be cooling the whole house through just a few vents upstairs and then “flowing†down the steps to cool the downstairs until the whole house is cooled. This seems to be inefficient. Since it is cooling the downstairs anyway (open stairwell), would it be more efficient to turn off the zoning system so that all the vents operate at one time and therefore utilizing the whole system to cool the whole house?

Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. User avater
    BillHartmann | Jul 04, 2002 06:44pm | #1

    " This seems to be inefficient."

    Now do you define EFFICIENT. As an engeering term it is the amount of energy output by a system vs the energy input. In the case of AC is would be the amount of cooling vs the electrical power. Is this how you are using the term?

    You did not say anything about comfort problems.

    If you have did have the lower vents open you will still the warm air from the 1st floor rising and the cool air from the 2nd floor falling so that you would probably over cool the first floor.

    How I have a 2 story house with equal sq ft on each floor. The first floor is slab on grade, partial earth contac, with lots of glass. The 2nd is conventionaly framed and less glass. Since these are two completely different enviroments I have two separate systems (this was before zoning was "common"). But I only have AC on the 2nd floor.

  2. TLRice | Jul 08, 2002 02:52pm | #2

    The only way to effectively zone a forced air system of the size and type that are common to residential applications, is multiple, separate systems. You said nothing about the ductwork, location of supply and return registers.

    Would it be more efficient to disable the zone controls and let the unit run? It would be as efficient. Depending on how the zones are setup and controlled and wether are not there are minimum flows maintainaed and if the system is sized properly for only one zone to be satisfied at a time.

    If it were my house, I would never have bothered with zoning. As you can tell, it doesn't work. In a house, zoning is most often an expensive gizmo taht does little to improve the comfort or efficiency(energy use for a given effect) of the residence. The money is better spent in the ductwork and the equipment. That doesn't help you, though, does it. Putting enough cold air in the 700 sf to cool the remaining 1750 from the top down would not be the best way to go.

    Do you have programmable thermostats? Can you get them? I would let the system operate as good as it can, but program the zones to be the way you want them when you use them, i.e. Upstairs (bed and bath), cool in the evening and night; downstairs (kitchen, den, dining, family) cool during the day when people are downstairs.

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

Podcast Episode 693: Old-House Hazards, Building Larsen Trusses, AI in Construction

The crew talks about work start times, fire-resistant construction, fixer-uppers, building Larsen trusses, and AI for construction.

Featured Video

A Modern California Home Wrapped in Rockwool Insulation for Energy Efficiency and Fire Resistance

The designer and builder of the 2018 Fine Homebuilding House detail why they chose mineral-wool batts and high-density boards for all of their insulation needs.

Related Stories

  • Podcast Episode 693: Old-House Hazards, Building Larsen Trusses, AI in Construction
  • FHB Podcast Segment: Finding Hazardous Materials in a Fixer-Upper
  • A Classic Paint Sprayer Gets a Thoughtful Refresh
  • Podcast Episode 692: Introduction to Trade Work, Embodied Carbon, and Envelope Improvements

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2025
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data