ADU Lending, Home Equity Loans, One Time Close,

Below is a list of non-bank lenders and Fannie Mae and Freddie Mac web page links discussing these mortgage programs. 

MSI Lending of Lexington         https://www.msilending.com/blog/22709/fha-loans/energy-efficient-mortgage-program

Green Finance Institute          https://www.greenfinanceinstitute.com/products-solutions/unsecured-green-home-loans/

Rocket Mortgage                                                                           https://www.rocketmortgage.com/learn/energy-efficient-mortgage

Guild Mortgage                                     https://www.guildmortgage.com/mortgage-loans/energy-efficient-mortgage-program/

FHFA Links:

                Fannie Mae                                                          https://yourhome.fanniemae.com/buy/youve-got-options-when-it-comes-home-financing

                                    Freddie Mac                            https://sf.freddiemac.com/working-with-us/origination-underwriting/mortgage-products/greenchoice-mortgages

Here's a credit union resource as they also seem to be specializing in these loan programs:

Clean Energy Credit Union    https://www.cleanenergycu.org/personal/green-home-improvement-loans/