By Oliver Style

Sg Mas Alba is a Mediterranean villa located in Sant Pere de Ribes, a municipality near the Garraf coast, south of Barcelona, Spain. Designed by the studio Sg Arq Passivhaus Architecture and developed by AXPRO, the home was certified to the Passive House Institute’s (PHI’s) Classic standard by Praxis Resilient Buildings.

The building has a robust thermal envelope with continuous insulation in the walls, roof, and floor and high-performance windows and glazing. It also has a minute amount of unwanted air infiltration, with an air permeability of 0.42 ACH50 (or a qe50 = 0.27 m³/h³m²). External shading devices—essential in the Mediterranean—include venetian blinds with variable slat angles (great for getting that balance between daylighting and solar control) and pergolas with retractable awnings (see Figure 1).

So, is this just another single-family Passive House? Not exactly. What makes this project interesting is that it’s been modeled and certified using a new tool called easyPH, which was developed by PHI precisely for single-family homes.

PHPP to easyPH: what is it?

Many of you who have worked in the design and construction of high-performance buildings to the Passive House standard will have heard of, or used, the PHPP (Passive House Planning Package). The PHPP is essentially a detailed, spreadsheet-based tool designed for the calculation of energy balances in buildings and for compliance verification with the Passive House standard. It was developed by PHI and calibrated using DYNBIL, a thermodynamic simulation program created by Dr. Wolfgang Feist, founder of the institute.

DYNBIL in turn has been used extensively to model real-life buildings, whose results have been compared with measured data across multiple buildings, showing good correlation. This careful calibration ensures that PHPP results closely align with real-world building performance, offering reliability in energy modeling.

PHPP was designed with simplicity and reliability in mind, making it approachable for construction professionals who may not be experts in thermodynamic modeling. If all models are wrong, then it’s probably better to be approximately correct than precisely wrong. More detailed (and in theory, more accurate) thermodynamic modeling tools can be a problem for the inexperienced user, as they have a huge range of data input parameters, which can easily lead to mistakes and meaningless results. So, PHPP is a great tool in that respect. But could it be made simpler, without skimping on accuracy?

Please welcome easyPH! easyPH is a simplified version of the PHPP 10.6, now in beta version 3. The tool maintains all the power and modeling features of the complete PHPP, but provides a stripped-down user interface, with only eight or so tabs visible along the bottom of the spreadsheet (compared with the 25+ tabs you are greeted with in the standard PHPP). easyPH is certainly less intimidating to the novice energy modeler!

There are similar time savings to be had when modeling the water heating system and night ventilation strategies. Overall, by using easyPH we tend to save on average five hours when we are certifying a single-family house and roughly twice that when we are first creating a model for such a home.

Take it easy!

PHPP energy modeling, despite its many advantages, can take up valuable time, particularly for designers who aren’t well acquainted with the tool. easyPH is an important step forward in making the design and certification process of certain Passive House buildings more agile and simpler, freeing up resources for the myriad of other tasks that are essential in making high-performance buildings a reality: good architectural design, HVAC planning, and site supervision!