Privacy Policy

Last updated: October 2026

This policy explains what information Supply & Return collects, how it is used and the choices you have. Supply & Return is a free set of HVAC calculators for room cooling loads, heat loss, airflow, duct sizes, SEER2 savings and ventilation rates. The tools are designed so that the measurements and figures you enter stay on your own device.

Summary

All calculations run in your browser. The values you enter, such as room areas, R-values, temperatures, airflow and electricity prices, are processed by JavaScript on your device and are not sent to our servers. We cannot see them and do not keep them. We receive only routine technical information about page visits, and, where advertising is shown, our advertising partner processes data as described below.

Information You Enter

The calculators accept values such as:

  • Room and envelope areas, ceiling heights and volumes
  • R-values, U-factors, design temperatures and air leakage rates
  • Heat loads, airflow, friction rates and duct velocities
  • Equipment capacities, efficiency ratings, cooling hours and energy prices

None of these values leave your browser. There are no accounts, no saved projects and no uploads of drawings or reports on our side, and you never need to enter your address. If a page remembers a convenience setting, such as your preferred area unit, it uses your browser's local storage, which you can clear at any time.

Information Collected Automatically

Our hosting and analytics systems receive standard technical data when a page loads:

  • Pages viewed and approximate time spent on them
  • Browser type, operating system, language and screen size
  • Approximate country or region derived from the IP address
  • The referring site or search engine
  • Server logs used to find errors and stop abuse, kept for a limited time

We use this in aggregate to understand which tools are useful, for example which calculators are used most at the start of the cooling season, to fix problems and to protect the site. We do not use it to identify you, and we do not sell it.

Cookies

We use a small number of cookies required for the site to function, such as one that records your consent choice. Where advertising is enabled, third-party vendors including Google may set cookies as described below. Our Cookie Policy explains how to manage them in your browser.

Google AdSense and Advertising

This site may display advertisements served by Google AdSense. Google, as a third-party vendor, uses cookies to serve ads on this site. Google's use of advertising cookies enables it and its partners to serve ads to you based on your visit to this site and other sites on the internet.

You can opt out of personalised advertising at Google Ads Settings, or opt out of some third-party vendors' use of cookies for personalised advertising at aboutads.info. Google explains how it uses information from sites that use its services at policies.google.com/technologies/partner-sites. Visitors in the European Economic Area, the United Kingdom and Switzerland are asked for consent before personalised advertising cookies are used. Ads may come from HVAC manufacturers or contractors; their appearance is not an endorsement, and we receive none of your calculator inputs to target them.

How We Use Information

  • To operate, maintain and secure the website
  • To understand aggregate usage and improve the calculators and guides
  • To reply to messages you send us
  • To display advertising that keeps the site free, where enabled

Values you enter into the calculators are not used for any of these purposes, because we never receive them.

Legal Bases

Where the GDPR or UK GDPR applies, we process technical data on the basis of our legitimate interest in running a secure and useful website, and we rely on your consent for non-essential cookies, including personalised advertising cookies, where consent is required.

Your Rights

If you are in the European Economic Area or the United Kingdom, you may request access to, correction of or deletion of your personal data, object to or restrict processing, withdraw consent at any time and complain to a supervisory authority such as the UK Information Commissioner's Office. California residents have rights under the CCPA to know what personal information is collected, to request deletion and not to be discriminated against for exercising these rights. We do not sell or share personal information for cross-context behavioural advertising beyond the Google advertising described above. Because almost all of our data is aggregated, we may be unable to link it to you. Email requests to logan.luo@adsnova.cn; we respond within 30 days.

Data Retention

Calculator inputs are never retained, because they never reach us. Aggregated analytics are kept for up to 26 months and server logs for a shorter period. Emails are kept only as long as needed to deal with your message.

Children's Privacy

This site is intended for adults and students in trade and technical courses. It is not directed to children under 13, and we do not knowingly collect personal information from children. If we learn that we have, we will delete it.

Third-Party Links

Guides may link to standards bodies, government efficiency programmes, utilities and manufacturer documentation. Those sites have their own privacy practices, which we do not control.

Changes

We may update this policy as the site or the law changes; the date at the top shows the latest revision.

Contact

Privacy questions: logan.luo@adsnova.cn.