< Draft of new Low Thermal Mass Sunspace Section >



Low Thermal Mass Sunspaces for Home Space Heating (and many other things)
Low thermal mass sunspaces provide an exceptional combination of advantages:  very efficient space heating for the home they are attached to, added living space that can be used for a wide variety of purposes, a wide range of cost effective designs, and they can also look great (a plus for HOAs and spouses).

This section provides a design guide to explain what its all about, test data that documents their heating efficiency, and quite a few example low thermal mass sunspaces.

Design Guide for Low Thermal Mass Sunspaces,

This design guide covers low thermal mass sunspaces -- including:

  • What they are.
  • How and why they work well.
  • Covers the design rules for goes over the design rules.
  • Testing demonstrating the heat output and efficiency.
  • The multi-purpose space advantages and uses.
  • What they don't do well.
 Low Thermal Mass Sunspaces for Space heating

Transparent, Walk-In Enclosure Installed Along South Side of Existing House and Used to Heat the house,
William Shurcliff

Nick Pine usenet post on low thermal mass sunspaces...


low thermal mass sunspaceThe two articles listed to the left explain how low thermal mass sunspaces work, and why they are so effective for space heating.

In a nutshell, if your main goal for the sunspace is house space heating, you don't want to waste solar heat heating up mass out in the sunspace.
Testing the Heating Performance and Efficiency of a Low Thermal Mass Sunspace

sunspace for space heating

sunspace heating performancesunspace temperaturesThis is a testing I did to measure the heating performance and efficiency of a low thermal mass sunspace for space heating. 

In addition, it provides temperature surveys of the space, thermal images, and some thoughts on designing for a combination of good space heating and a comfortable space to spend time in.

The sunspace performs very well as a space heater -- on par with high quality active collectors -- and you can read your paper and catch a few rays.

All the details...
Example Low Mass Sunspaces
Some examples of low thermal mass sunspaces that shows some of the huge range of  possibilities.
Mike's Low Thermal Mass, Multi Purpose Sunspace in the Colorado Mountains

Colorado low mass sunspaceThis is Mike's low thermal mass sunspace in Colorado.  It is used for a variety of purposes including heating the house, drying clothes, kids play room, drying food, and reading the paper.  In addition to all those uses, Mike is currently working on a way to integrate solar water heating into the sunspace.

An exceptional job of blending the added sunspace with the existing house. 
The variety of purposes that sunspaces can be put is what makes them exceptional -- drying clothes alone saves about 1200 KWH and 2000 lbs of CO2 a year.

Mike provides all the details on the design, build, and performance...
Nick Pine's Innovative Three Story Sunspace

All the details on Nick's sunspace...
innovative sunspaceThis is Nick's new and cutting edge three story sunspace. 

It includes a number of innovative features such as custom made DIY double glazing, an experimental mesh system to improve collection efficiency, and a unique heat distribution system.

All the details on Nick's sunspace...

Low Thermal Mass Sunspace in Minnesota,
William Sikora




Architect William Sikora describes his design for a modern and elegant sunspace for this Minnesota home.

The air distribution and control system is very simple, and designed to be maintained by the home owner with only simple tools.

Certainly a beautiful and cost effective addition to the home.

All the details on this modern, elegant sunspace...
Norman Saunders Cliff House

Cliff house by Norman Saunders (pdf)


The Cliff house designed by Norman Saunders uses a large, 2 story, low mass sunspace across the front of the house that provides 100% of the heating demand for the house all year.

The sunspace is coupled with heat storage systems in the attic and crawl space that allow the home to achieve 100% solar heating.
Instant Sunspaces  -- How cheap can a sunspace be?

Laren Corie

Download the Feb, 2005 issue


Ed's Zero Cost Sunspace ...

ESSN Journal, Feb, 2005

A good article by Laren Corie on how to build and experiment with inexpensive sunspaces.  The example used in the article cost a grand total of $22, and went together in a couple hours!

A free download.


Here is another very low cost (actually zero cost) sunspace done by Ed.   Details ...

This shows how inexpensive and easy it is to turn a porch into a sunspace that is pleasant to spend time in, and can supply some heat to the house.

Air based solar-thermal “Hot-Box” collector

Full details on "Hot Box" collector...
solar thermal hot box collectorMitch calls this a "Hot-Box" collector, but I think it could equally be called a mini-sunspace.

Very nicely built -- as Mitch says, its "wife approved".

Some performance estimates provided.

Note the use of the reflector to improve collection -- reflectors are particularly effective in that they increase collection area without increasing heat loss.
I would pass on the idea of adding rocks for heat storage for the reasons discussed above -- unless you have a way of insulating the glazing at night.