How should you go about a deep retrofit of an existing house? These are our 10 steps.
Coincidently, the excellent Reimagine Buildings have just issued their 10 Steps To Designing Your First Passive House” video. https://www.youtube.com/watch?v=zA0oKPw2cas.Our steps assume you have already got the design advice in place.
Deep Retrofit. Whole building analysis and upgrade as a system, to set targets, that will provide an overall significant reduction in energy use while increasing comfort, indoor air quality, and eliminating moisture and mould that affect our health and durability of the building.
EnerPHit. An established standard for high energy efficiency retrofits from the Passive House Institute. It is a tried and tested method of designing for performance with reliable results.
1. Research – get together all the information you can You need accurate plans. Finding copies of details is invaluable.
2. Sketch Retrofit Concept – Doe you insulate internally or externally? What is the thermal envelope? Where does the airtight layer go? How do you route the ventilation? Sketch the tricky details?
3. Initial designPH and PHPP Analysis – Test your ideas and try different options. designPH is a Sketchup plugin where you can model geometry, insulation, and shading. It will give rough results. You can test options and then refine them in PHPP.
4. Get Some Advice and Feedback on Results – Now you have some modelling and sketch details, it’s a good chance to get advice. We had some initial consultation with Sustainable Engineering, the certifier, plus advice on detailing from Soren at Proclima.
5. Windows, Doors and Ventilation – Let's Go Shopping – Now you know what level of performance you are looking for in your components, it’s time to shop for the specific products and get advice from suppliers and manufacturers. Can they supply the required information? Test them in the model.
6. Pre-Construction Submission – Finalise your modelling, now with specific values for windows, doors, and ventilation. Include any required thermal break modelling. Finalise details and documentation. Submit to the certifier to check your model.
7. Team Briefing – All of the people working on the construction need to work together, understanding the why and the what of the refurbishment. Some of the techniques will probably be new. The sequence of work can be very important to allow certain tasks to be done. It’s hard to go back and redo things later.
8. Expect The Unexpected – Something is always going to pop up during construction, especially with existing buildings. So far, we have found concrete floors at different levels for what must have been a laundry and porch. These need to be designed around and the model updated. (or hire a jackhammer!)
9. Blower Door Tests – These need to be carefully planned through construction. Ideally, there is a builder’s test, maybe Proclima can help, a B test when the air control layers are still exposed, and a final A test when the house is complete.
10. Final Review and Certification – Any final tweaks to the modelling. Photos are needed of all parts of the construction, blower door test results, and ventilation commissioning. This provides quality control for the refurbishment and reassurance that the home will perform as intended.