Half of a sample of 52 secondary schools built in England in the last five years were at best "mediocre", government design advisers say.
One of the best designs: Caroline Chisholm School, Northants
The design quality was "not good enough to secure the government's ambition to transform our children's education".
The report by the Commission for Architecture and the Built Environment (Cabe) coincides with an inquiry by MPs into Building Schools for the Future.
The government says it has already taken steps to raise standards.
Under the multi-billion-pound scheme, all secondary schools and half of all primaries are to be transformed over 15 years.
A spokesman for the Department for Education and Skills (DfES) said: "The report represents a retrospective look at school design which does not bear any resemblance to where we are now."
It had taken steps, including enlisting Cabe to advise on individual projects, to ensure that high-quality design was "an absolute priority".
The government's ambition to transform school buildings is about not just replacing those that are crumbling but also about transforming learning.
Cabe audited a representative sample of 52 of the 124 schools that had been completed.
The three criteria were functionality, build quality, and "ability to create a sense of place" with "an uplifting effect" on the local community.
It found 10 that were good or excellent - four of which were new academies - 15 were "partially good", 11 "mediocre" and 16 "poor".
"Those ranked as poor were considered particularly bad at providing inspirational educational environments, and nearly all schools failed to tackle basic issues of environmental sustainability such as providing natural daylight and ventilation," Cabe said.
All but one of the poorest 10 had been built under the private finance initiative (PFI), and only three of the best 10.
Cabe's chief executive, Richard Simmons, said: "On average, five schools will be rebuilt or refurbished every week for the next 13 years.
"This really is a once-in-a-lifetime opportunity to improve our children's education and we need to make sure we get it right."
Among Cabe's recommendations, DfES should fund a review of school design briefs, which it said had hardly changed for 20 years.
There are signs that local authorities initially struggled with the sheer scale of what Building Schools for the Future involves, as it is rolled out in a series of "waves".
In a letter to concerned parties earlier this month, the head of schools capital at the DfES, Sally Brooks, said: "So far in waves 1 to 3 progress has been steady but there is a need for those projects to maintain their focus on delivery."
She warned that "delays mean increased costs as construction inflation eats into the value of our budget".
An official evaluation of the first waves catalogued the shortcomings:
There was an emphasis in the government's vision for 21st Century schooling that ICT (information and communication technology) would be crucial in transforming the way children learn.
- Project teams under-resourced
- Problems getting suitable managers
- Timescales sometimes "overly optimistic"; plans neglected
- Risk management processes often "ineffective"
But the evaluation said: "The impact of ICT and the mechanism for delivering it to schools is often unclear to authorities until well into the procurement process and is not always regarded as a high priority."