How can we do Search for unread mails in FolderId method

Hi all,

I am using Exchange server 2013,

My Admin user Account has Access to all Mail Boxes in Exchange server.

Now I am getting  all Mails of any User [ex: venkat@admin.com] using FolderId Method,  but  i need to only get Unread Mails of the User [ex: venkat@admin.com].

Here is my Code

 ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2013);
            service.Credentials = new WebCredentials("Administrator@admin.com", "EIS2014!@#");
             service.AutodiscoverUrl("Administrator@admin.com");

            var userMailbox = new Mailbox("venkat@admin.com");
            var folderId = new FolderId(WellKnownFolderName.Inbox, userMailbox);

            var itemView = new ItemView(20);   
            var userItems = service.FindItems(folderId, itemView);

            foreach (var item in userItems)
            {
                item.Load();

                var senderEmail = ((EmailMessage)item).From;
                var subject = item.Subject;
                var body = item.Body;
            }

How can i do search for Unread mails in FolderId Method

I know Search filter can search for unread Mails,

here is the code for that

 SearchFilter searchFilter = new SearchFilter.SearchFilterCollection(LogicalOperator.And, new SearchFilter.IsEqualTo(EmailMessageSchema.IsRead, false));

            ItemView view = new ItemView(50);

            FindItemsResults<Item> findResults = service.FindItems(WellKnownFolderName.Inbox, searchFilter, view);

How can i add above Search Filter for FolderId Method to get Unread mails?