public class ValidationErrorAttribute : FilterAttribute, IExceptionFilter
{
public virtual void OnException(ExceptionContext filterContext)
{
    if (filterContext == null)
    {
        throw new ArgumentNullException("filterContext");
    }

    if (filterContext.Exception != null)
    {
        filterContext.ExceptionHandled = true;
        filterContext.HttpContext.Response.Clear();
        filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
        filterContext.HttpContext.Response.StatusCode =
        (int)System.Net.HttpStatusCode.BadRequest;
        //return the partial view containing the validationsummary and set the ViewData
        //so that it displays the validation error messages
        filterContext.Result = new PartialViewResult { ViewName = "validation",
        ViewData = filterContext.Controller.ViewData  };
    }
}
}

//Controller
    [HttpPost]
    [ValidationErrorAttribute]
    public ActionResult Save(ConsumptionData consumptionData)
    {
        if (ModelState.IsValid)
        {
            var dto = Mapper.Map<ConsumptionData, ConsumptionDataDto>(consumptionData);
            var refId = _personalProjectionRepository.AddPersonalProjectionRecord(dto);
            consumptionData.ReferenceId = refId;
            return PartialView("Reference", consumptionData);
        }
        else
        {
            throw new ValidationException();
        }
    }

@model PersonalProjection.Web.Models.ConsumptionData
       @Html.ValidationSummary()

$('form').submit(function () {
        var form = $(this);
        if (form.valid())
        {

            $.ajax({
                url: form.attr("action"),
                type: "POST",
                dataType: "html",
                contentType: "application/json; charset=utf-8",
                data: JSON.stringify({
                    SiteId: $('#siteid').val(),
                    ElectricityConsumption: $('#electricityconsumption').val(),
                    ElectricitySpend: $('#electricityspend').val(),
                    GasConsumption: $('#gasconsumption').val(),
                    GasSpend: $('#gasspend').val()
                }),
                success: function (result) {
                    $('#rightPanelSection').html(result);
                },
                error: function (jqXHR) {
                    $('#validationSummary').html(jqXHR.responseText);
                }

            });
        }
        return false;
    });

<div class="panel panel-outcome">


 @using (Html.BeginForm("Save", "Home", FormMethod.Post, (object)new { ID  =
 "projectionForm" }))

{
<div id="validationSummary"/>

<div id="topPanelSection" class="panel-section">
    @Html.LabelFor(m => m.SiteId, new { id = "siteidlabel" })
    @Html.TextBoxFor(m => m.SiteId, ViewBag.TextBoxDisabled ? (object)new { id =
    "siteid", disabled = true, maxlength = 9, @class = "input-disabled", @Value =
    ViewBag.SiteId } : new { id = "siteid", maxlength = 9 })
    <span id="errorText" class="error-text" />
</div>
<div id="leftPanelSection" class="panel-section">
    <div class="column-heading">
        <span class="column-heading-left">Total Cost</span>
        <span class="column-heading-right">Total Consumption</span>
    </div>
    <div class="panel-section-row">
        @Html.LabelFor(m => m.ElectricitySpend, new { id = "electricitylabel" })
        <span>£</span>
         @Html.TextBoxFor(m => m.ElectricitySpend, new { @class = "textbox-right-
         margin", id = "electricityspend" })
         @Html.TextBoxFor(m => m.ElectricityConsumption, new { @class = "textbox-
         left-margin", id = "electricityconsumption" })
        <span>kWhs</span>
    </div>
    <div class="panel-section-row">
        @Html.LabelFor(m => m.GasSpend, new { id = "gaslabel" })
        <span>£</span>
         @Html.TextBoxFor(m => m.GasSpend, new { @class = "textbox-right-margin", id =
         "gasspend" })
         @Html.TextBoxFor(m => m.GasConsumption, new { @class = "textbox-left-margin",
         id = "gasconsumption" })
        <span>kWhs</span>
    </div>
    <div class="panel-section-row">
        <button type="reset" id="resetbutton">Reset Form</button>
        <button type="submit">Generate Reference Id</button>
    </div>
</div>
<div id="rightPanelSection" class="panel-section">
    @Html.Partial("Reference", Model)
</div>

$('#validationSummary').html(jqXHR.responseText);

<div id="validationSummary"/>

<div id="validationSummary">

    </div>