Passive Solar Porch Reno – Part 1

in Home Energy

Stonehaven's South-facing Porch I’ve been thinking about this for a decade… turning my south-facing front porch into a passive solar heater on those sunny winter days. This was the year I really had to do something with the peeling paint and loose window glazing, as well as the crumbling concrete steps that had become downright dangerous to use.

My wish list includes incorporating a more traditional exterior facade as well as saying goodbye to the 70’s-era wall panelling and acoustical ceiling tile. This is currently a work in-progress and the first in a short series on the project.

The Why

If you’re familiar with Stonehaven Life you may already know I’m a big fan of taking advantage of the free heat from the sun when it’s available to help reduce our dependency on other energy sources. Here in New Brunswick, Canada the coldest days of winter often come with clear blue skies and sunshine – perfect conditions for harnessing passive solar heat.

While my porch has a near-perfect orientation for capturing the sun’s heat – it all leaks out though the windows, door, walls and ceiling.

original single pane wood sash1970's wood panelling and acoustical tileLet me be clear – I’m enough of a realist to understand this ‘to the studs’ reno isn’t ever going to ‘pay for itself’ in reduced energy bills in my lifetime. But I do hope that instead of looking though the living room window in January at the indoor porch thermometer reading -20C(-4F) – I’ll be able to let  warm +20C(68F) air waft into the house for a few hours and have my mid-afternoon coffee in a bright comfy porch on those sunny winter days ahead. I’ll soon find out.

The What

Aluminum siding and peeling paintAfter a bit of research and consultation with a local  passive house designer I came up with a plan. I had a budget figure in mind and set the criteria for the project. Although the main focus was on passive heating – aesthetics and low maintenance were also high on my list of priorities. IMGP3562A metal roof was installed last year so that’s off my list. 

As with my veranda project a few years back, I hired a contractor to do the framing, windows and siding and I’ll do the finish work inside and out as time allows over the winter months. Here’s a breakdown of the project priorities:

  • Windows – new double glazed, low E, Argon filled Vinyl-clad windows with muntins replicating the original 3 over 1 single glazed wood sashes.
  • Door – replace the sagging aluminum storm door (R-0) with an insulated exterior door.
  • Insulation – add 2" rigid foam insulation (R-10) to the exterior including the concrete foundation to 6" below grade. Add as much insulation to ceiling and walls as possible and seal up all the air leaks.
  • Siding – replace wide aluminum siding with 4" vinyl siding to match existing siding on the house
  • Exterior Trim – replace wood trim with PVC material – adding architectural details such as a continuous sill, corner boards and fascia appropriate to the original house.
  • Deck – design a deck that can be built without removing the existing concrete steps that will tie the house to the front yard
  • Railings – minimal railings that don’t require maintenance.
  • Interior – complete makeover including refurbishing the original shingled house exterior wall 

The Passive Perspective

Aluminum storm door has no insulation value Since this space has no other heating source, there are a number of factors that will affect the performance based on the building ‘science’ as it stands. In winter, the porch temperature will change drastically from day to night and will likely be too cold to use during cloudy weather. On those days and nights it will still continue to help reduce heat loss through the front of the house relative to before insulating the space.  In summer, I may need to add window shades if the porch tends to overheat even with the windows open.

There are a number of accepted design principles associated with passive solar building since the 1970’s. I’ve incorporated some and will ‘experiment’ with others that some experts deem to be less important as building materials and techniques have improved.

  • Site Orientation: My porch faces slightly South-Southwest. In mid-winter the rising sun shines in the end windows and sets facing the front.
  • Shading: The large maple tree shades the porch from afternoon sun in summer. The tree sheds it’s leaves in October so it gets full sun all day long in winter.
  • Window Area: All those windows are a double edged sword – plenty of solar gain on a sunny day and significant heat loss the rest of the time.
  • Thermal Mass: I’ve ignored the thermal mass element on the basis of it slowing the ‘response time’ of the porch. I’d rather it heat and cool rapidly than take all day to warm up a large thermal mass after a several cold cloudy days.
  • Insulation and Air Sealing: I’ve concentrated my efforts on air sealing, insulation and managing the air exchange between the porch and the house since I’m home during the days.

The Process

Original shingles on front wall of houseThis project addresses a variety of personal passions and exploration of ideas. It’s as much about the design process, experimentation and problem solving for me as anything else – so I’m not in any particular rush to get to the finish line.

Let the demolition begin!

 
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Passive Solar Porch Reno – Part 2
 
 

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