I suppose many parts of California have optimal conditions and so the payback will be quite good.
I think it is hard to disuse these issues in general because requirements vary so much by location.

I don’t see how a white roof is going to cool the underside of solar panels. The purpose of the white is to reflect energy.

I used the DOE calculator to look at the cost savings from the most reflective surface I could find and for my location it did not pay for itself. (when the roof itself is very well insulated) But I would guess that there would be a cumulative effect in urban areas.

Clearly many architects are thinking about it. I am not an architect but I like passive design and have thought it was cool and underutilized most of my life. I would like to use it more but my clients do not want what I would consider to be good design. In general they only seem to want a house that is more impressive than their neighbors.

When they do talk about ‘green’ they are generally so confused by the hype that their expectations are unrealistic.

I suppose many parts of California have optimal conditions and so the payback will be quite good.
I think it is hard to disuse these issues in general because requirements vary so much by location.

I don’t see how a white roof is going to cool the underside of solar panels. The purpose of the white is to reflect energy.

I used the DOE calculator to look at the cost savings from the most reflective surface I could find and for my location it did not pay for itself. (when the roof itself is very well insulated) But I would guess that there would be a cumulative effect in urban areas.

Clearly many architects are thinking about it. I am not an architect but I like passive design and have thought it was cool and underutilized most of my life. I would like to use it more but my clients do not want what I would consider to be good design. In general they only seem to want a house that is more impressive than their neighbors.

When they do talk about ‘green’ they are generally so confused by the hype that their expectations are unrealistic.

I like the house – don’t get me wrong on that point – however with all that glass & high ceilings – zero energy? Even with the best windows & lots of exterior insulation the house still will ‘eat’ energy.

Actually the water temperature at 50 foot depth a given location varies maybe 2 degrees F over the course of a year. The underground temperature in the north east of CA is typically 52 while the San Diego area is listed as 72 degrees. There are charts available about this on the net.

With hydronic cooling you typically end up using fan coils. For ‘in floor cooling’ you need to stay above stay above the condensation temperature which gives little cooling. If you don’t stay above the condensation temperature you will have a horrible mess with wet everywhere. The fan coils require a certain delta T across the unit to function which in turn requires the heat pump – either GSHP (geothermal source) or ASHP (air source). Even 50 degree water is marginal for fan coil cooling – with 60 degree water you can forget it.

As you might guess I have been through this recently in building my new home.

I have seen the data on the amount of energy expended in making solar panels vs. the energy return. In a decent solar location they are very positive. In Seattle, WA probably never.

Passive solar could be used very much more than it is around the world – same with solar air heat.

Have a great day!,
Russ

I like the house – don’t get me wrong on that point – however with all that glass & high ceilings – zero energy? Even with the best windows & lots of exterior insulation the house still will ‘eat’ energy.

Actually the water temperature at 50 foot depth a given location varies maybe 2 degrees F over the course of a year. The underground temperature in the north east of CA is typically 52 while the San Diego area is listed as 72 degrees. There are charts available about this on the net.

With hydronic cooling you typically end up using fan coils. For ‘in floor cooling’ you need to stay above stay above the condensation temperature which gives little cooling. If you don’t stay above the condensation temperature you will have a horrible mess with wet everywhere. The fan coils require a certain delta T across the unit to function which in turn requires the heat pump – either GSHP (geothermal source) or ASHP (air source). Even 50 degree water is marginal for fan coil cooling – with 60 degree water you can forget it.

As you might guess I have been through this recently in building my new home.

I have seen the data on the amount of energy expended in making solar panels vs. the energy return. In a decent solar location they are very positive. In Seattle, WA probably never.

Passive solar could be used very much more than it is around the world – same with solar air heat.

Have a great day!,
Russ

Studies have been conducted showing that highly reflective roof surfaces actually attribute to accelerated degradation of the building facades immediately adjacent and above these high albedo surfaces. UV is the main destructive component of any exterior material. When it’s reflected off of a white roof, it intensifies the UV exposure on material that was never rated to withstand such high levels of exposure.

So on the surface, yes; cool reflective roofs are a good idea, but like anything they should only be done if warranted and practical for not only the building it’s going on, but the surrounding buildings as well. I don’t think it speaks to much for sustainability if you’re essentially speeding up the destruction of the buildings surrounding you.

Studies have been conducted showing that highly reflective roof surfaces actually attribute to accelerated degradation of the building facades immediately adjacent and above these high albedo surfaces. UV is the main destructive component of any exterior material. When it’s reflected off of a white roof, it intensifies the UV exposure on material that was never rated to withstand such high levels of exposure.

So on the surface, yes; cool reflective roofs are a good idea, but like anything they should only be done if warranted and practical for not only the building it’s going on, but the surrounding buildings as well. I don’t think it speaks to much for sustainability if you’re essentially speeding up the destruction of the buildings surrounding you.