diff --git a/caimira/apps/calculator/__init__.py b/caimira/apps/calculator/__init__.py
index 401849d7..3002f6f1 100644
--- a/caimira/apps/calculator/__init__.py
+++ b/caimira/apps/calculator/__init__.py
@@ -29,7 +29,7 @@ import tornado.log
 
 from . import markdown_tools
 from . import model_generator, co2_model_generator
-from .report_generator import ReportGenerator, calculate_report_data
+from .report_generator import ReportGenerator, calculate_report_data, img2base64, _figure2bytes
 from .user import AuthenticatedUser, AnonymousUser
 
 # The calculator version is based on a combination of the model version and the
@@ -39,7 +39,7 @@ from .user import AuthenticatedUser, AnonymousUser
 # calculator version. If the calculator needs to make breaking changes (e.g. change
 # form attributes) then it can also increase its MAJOR version without needing to
 # increase the overall CAiMIRA version (found at ``caimira.__version__``).
-__version__ = "4.13.0"
+__version__ = "4.14.0"
 
 LOG = logging.getLogger(__name__)
     
@@ -390,7 +390,7 @@ class CO2Data(BaseRequestHandler):
             report = await asyncio.wrap_future(report_task)
         
             result = dict(report.CO2_fit_params())
-            result['fitting_ventilation_type'] = 'fitting_natural_ventilation'
+            result['fitting_ventilation_type'] = form.fitting_ventilation_type
             result['transition_times'] = report.ventilation_transition_times
             result['CO2_plot'] = self.generate_ventilation_plot(form.CO2_data, report.ventilation_transition_times, result['ventilation_values'])
             self.finish(result)
diff --git a/caimira/apps/templates/base/calculator.form.html.j2 b/caimira/apps/templates/base/calculator.form.html.j2
index f7a4bc91..c12cb6c0 100644
--- a/caimira/apps/templates/base/calculator.form.html.j2
+++ b/caimira/apps/templates/base/calculator.form.html.j2
@@ -344,15 +344,15 @@
                 <img id="CO2_data_plot"/><br>
                 <strong>Ventilation scheme:</strong>
                 <div>
-                  <input class="ml-2" type="radio" id="fitting_natural_ventilation" name="fitting_ventilation_type" value='fitting_natural_ventilation' checked="checked" data-enables="#DIVfitting_natural_ventilation">
+                  <input class="ml-2" type="radio" id="fitting_natural_ventilation" name="fitting_ventilation_type" value='fitting_natural_ventilation' checked="checked" data-enables="#DIVfitting_natural_ventilation" form="not-submitted" >
                     <label for="fitting_natural_ventilation">Natural</label>
-                  <input class="ml-2" type="radio" id="fitting_mechanical_ventilation" name="fitting_ventilation_type" value='fitting_mechanical_ventilation'>
+                  <input class="ml-2" type="radio" id="fitting_mechanical_ventilation" name="fitting_ventilation_type" value='fitting_mechanical_ventilation' form="not-submitted">
                     <label for="fitting_mechanical_ventilation">Mechanical</label>
                 </div>
 
                 <div id="DIVfitting_natural_ventilation" class="form-group mb-0" style="display: none">
                   <label for="fitting_ventilation_states">Please enter the ventilation state change times, separated by comma - e.g. [8.5, 10, 11.5, 17] </label>
-                  <input type="text" class="form-control" id="fitting_ventilation_states" name="fitting_ventilation_states" placeholder="e.g. [8.5, 10, 11.5, 17]"><br>
+                  <input type="text" class="form-control" id="fitting_ventilation_states" name="fitting_ventilation_states" placeholder="e.g. [8.5, 10, 11.5, 17]" form="not-submitted"><br>
                 </div>
               </div>