I want to display only the child nodes with the checkbox value "Technology" selected, value 252 in my checkbox list.

I have two macros, one that displays thumbnails of the child nodes (ProjectsAlbum.xslt) and one that is a filter for refining the child nodes to specific values, via options selected in a select menu (ProjectsFilter.xslt) .

I've created a datatype checkbox list (Project Type) with the following:
Text                          Value
Fitout                        149
Refurbishment          150
Heritage                    227
Sustainability            228
New Build                 230
$5 Million+                249
Government             251
Technology              252

How can I make the default value of the select menu "Techology" and therefor only display child nodes with that checkbox checked?

Do I need to make the change to the Projects Album which is pulling in all the child nodes or do I make the change to the Projects Filter?

Here's the ProjectsAlbum.xslt:

 <xsl:variable name="possibleNodes" select="$currentPage/ancestor-or-self::root//*
 [@isDoc and string(./umbracoNaviHide) != '1' and name() != 
'ProjectGallery' and name() = 'ProjectPage']" />

Here's the ProjectsFilter.xslt:

      <fieldset>
        <xsl:variable name="projectTypeList" select="umbraco.library:GetPreValues(1212)//preValue" />
        <select name="projectType" id="projectType"  onchange="document.getElementById('aspnetForm').submit()" >
          <option value="">All project types</option>
          <xsl:for-each select="$projectTypeList">
            <xsl:sort order="ascending" data-type="text" />
             <option value="{.}">
               <xsl:if test="$FF_projectTypeList = .">
                 <xsl:attribute name="selected">selected</xsl:attribute>
               </xsl:if>
              <xsl:value-of select="." />
            </option>       
          </xsl:for-each>
        </select>        
      </fieldset>