An HTML page is not dynamically processed by ASP.NET when it is requested. If the browser is requesting an HTML page, it is always going to get the HTML as written.
For example, if you have an html page named Info.html, and a browser requests Info.html, the server will return the html that is contained in that page.
However, if you have an aspx page named Info.aspx, then when the browser requests Info.aspx, the server will run the code in Info.aspx along with its code behind page code if it exists, and returns the html that is dynamically generated.
If you only want the aspx code to run occasionally, there are ways to cache the output so that it is only regenerated when the conditions exists that warrant it.